bluuebunny/crossref_metadata_2025 huggingface dataset:
METABOLIC INHIBITORS AND CHROMOSOME REJOINING
Authors: Beatty Alvin V. , Beatty Jeanne W.
Published: January 2018

Beatty, Alvin V., and Jeanne W. Beatty. (Emory U., Atlanta, Ga.) Metabolic inhibitors and chromosome rejoining. Amer. Jour. Bot. 46(5): 317–323. 1959.—X ray‐induced chromosomal aberrations of the dicentric and ring types in the first microspore division in Tradescantia paludosa were used to study the effects of temperature and chemical substances acting as metabolic modifiers on rejoining under both aerobic and anaerobic conditions. A total dose of 400 r of x rays was administered at 50 r/min. at temperatures ranging from 0.3°C. to 45°C. In the aerobic temperature experiments, 5% oxygen was used in either helium or carbon monoxide and in the anaerobic ones helium was used. In 5% oxygen in helium, the highest number of aberrations was produced at the lowest temperature. When the amount of oxygen in solution was made constant at all temperatures by adjusting the positive pressure of gas in experiments carried out above zero degrees, there was a temperature effect at 0.3°C. and 10°C., but no effect from 20°C. to 45°C. Temperature was believed not to influence chromosome breakage but only rejoining, through its influence on oxidative metabolism, thereby removing the source of energy. In the anaerobic temperature experiments, a low aberration yield of 0.14 occurred at 0.3°C., while a high of 0.66 was recorded at 40°C. Cytochrome oxidase was found not to be involved in the energy supply for rejoining in anaerobic experiments, since exposures in alkaline pyrogallate‐washed carbon monoxide gas gave the same results as helium, indicating that both gases only provide anoxic conditions. Under anoxic conditions, pretreatment in M/1000 sodium iodoacetate or M/10,000 p‐chloromercuribenzoate solutions had no effect on non‐irradiated plants thus treated, but increased the average number of chromosome aberrations per cell produced by x rays at least 2‐fold over the irradiated controls. The effect of these 2 salts, as used in these experiments, is believed to have taken place through their inactivation of triosephosphate dehydrogenase, thus inhibiting glycolysis at an early stage before any energy was released.
ANEUPLOIDY IN CLAYTONIA VIRGINICA
Authors: Rothwell Norman V.
Published: January 2018

Rothwell, Norman V. (Long Island U., Brooklyn, N. Y.) Aneuploidy in Claytonia virginica. Amer. Jour. Bot. 46(5): 353–360. Illus. 1959.—Within the taxon, Claytonia virginica L., an extensive aneuploid series has been found including the following chromosome numbers: 2n = 12, 14, 16, 17, 18, 19, 20, 22, 24, 26, 28, 30, 32, 34, 36, 48, and 72. Studies revealed that a population could be composed of individuals differing in chromosome number. Pollen fertility appears to be high in natural populations and in plants showing meiotic irregularities. Different karyotypes were found within the taxon; plants having the same chromosome number may have different karyotypes. Hybrids have been obtained as the result of crossing plants differing both in number and karyotype. From all the evidence, C. virginica appears to be able to tolerate transitions from one cytological type to another. The hypothesis is proposed that most of the various numbers have been derived from a haploid complement of 8 chromosomes possessing median centromeres. The following factors are suggested to account for the origin of the different numbers: nondisjunction, univalent lagging, misdivision of univalents, polyploidy, and fertile triploids.
SEX DETERMINATION IN DIPLOID‐TRIPLOID CROSSES OF SPINACIA OLERACEA
Authors: Mahoney D. L. , Janick Jules , Stevenson E. C.
Published: January 2018

Mahoney, D. L. Jules Janick, and E. C. Stevenson. (Purdue U., Lafayette, Ind.) Sex determination in diploid‐triploid crosses of Spinacia oleracea. Amer. Jour. Bot. 46(5): 372–375. 1959.—Segregation for sex in spinach was studied in a series of diploid pistillate × triploid staminate crosses. The genetic data indicated that the functional gametes from staminate triploids were not confined to n and n + 1 types. Cytological analyses of progenies from a number of 2n ♀ × 3n (XYY and XYY) ♂ crosses revealed similar but non‐homogeneous types of chromosome segregation. These crosses produced 49.3% diploids, 17.9% trisomies, 0.5% with 14 chromosomes, 1.2% with 16 chromosomes, 11.4% with 17 chromosomes, 18.9% triploids, and 0.8% with 19 chromosomes. The reciprocal crosses produced a higher percentage of aneuploid types including 1.7% with 15 chromosomes. Segregation for sex in each of the various chromosome numbered progeny of diploid‐triploid crosses was presented and analyzed.
SHOOT HISTOGENESIS: THE EARLY EFFECTS OF GIBBERELLIN UPON STEM ELONGATION IN TWO ROSETTE PLANTS
Authors: Sachs Roy M. , Bretz Charles F. , Lang Anton
Published: January 2018

Sachs, Roy M., Charles F. Bretz, and Anton Lang. (U. California, Los Angeles.) Shoot histogenesis: The early effects of gibberellin upon stem elongation in two rosette plants. Amer. Jour. Bot. 46(5): 376–384. Illus. 1959.—Within 24 hr. after the application of gibberellic acid (GA) to vegetative plants of biennial Hyoscyamus and of the long‐day plant Samolus, a considerable increase in mitotic activity was observed in the pith, cortical, and vascular tissues of the rosette axis immediately below the apical meristem. As the treatment continued, the zone of cell division increased commensurate with the increase in length of the stem; the new cell divisions formed transverse walls predominantly and thus contributed to stem elongation. The cell contribution from the apical meristem was but a small fraction of the total produced by the subapical tissues, suggesting that the induced subapical mitotic activity is the main site of tissue development in the shoot. There was no evidence for cell elongation for at least 72 hr. after application of GA, and, hence, the initial increase in stem length was due solely to an increase in cell number. With regard to the general problem of shoot histogenesis, our data for the rosette plants and those for Xanthium and Chrysanthemum showing extensive cell division far below the apical meristem, are in full agreement with the studies by Bindloss (1942) with tomato, and support her conclusion that “. . . it is no longer possible to think that the chief center of cell division is in a relatively short zone 60 to 100 microns from the stem tip . . . and that cell division activity in the promeristem is not solely responsible for stem length.” On the contrary, the mitotic activity in the subapical regions is undoubtedly responsible for the major part of the cells found in the stem.
CHROMOSOME NUMBERS IN THE HYPOCREALES 1. NUCLEAR DIVISION IN THE ASCUS OF NECTRIA PEZIZA
Authors: El‐Ani Arif S.
Published: January 2018

El‐Ani, Arif S. (Columbia U., New York, N. Y.) Chromosome numbers in the Hypocreales. 1. Nuclear division in the ascus of Nectria peziza. Amer. Jour. Bot. 46(6): 412–417. Illus. 1959.—The 4 nuclear divisions in the ascus of Nectria peziza were studied with the aid of acetoorcein and aceto‐carmine techniques. The ascus was found to arise by crozier formation. Synapsis takes place while the chromosomes are still contracted and elongation of chromosomes continues throughout the pachytene phase. The haploid complement was found to consist of 5 chromosomes, the second of which is the nucleolus‐organizing chromosome. This chromosome number which had never been reported in the Hypocreales was also found in several other species of this group of fungi. Chromosome numbers in the Hypocreales are discussed with regard to the species concept in the imperfect genus Fusarium.
AUTORADIOGRAPHIC STUDIES OF NUCLEIC ACIDS AND PROTEINS DURING MEIOSIS IN LILIUM LONGIFLORUM
Authors: Taylor J. Herbert
Published: January 2018

Taylor, J. Herbert (Columbia U., New York, N. Y.) Autoradiographic studies of nucleic acids and proteins during meiosis in Lilium longiflorum. Amer. Jour. Bot. 46(7): 477–484. Illus. 1959.—A study was made of the incorporation of glycine‐C14, orotic acid‐C14 and cytidine‐H3 into nucleic acids and proteins of sporogenous and tapetal cells of lily anthers preceding and during meiosis. Methods for differential extraction of nucleic acids from tissue sections, which had been frozen, dehydrated by alcohol‐substitution, and fixed in hot alcohol, were tested by chromatographic analysis of extracts. Both acid and enzyme hydrolysis were shown to be useful for quantitative or, at least, semi‐quantitative work. DNA synthesis was shown to occur only during premeiotic interphase in sporogenous cells, but at two intervals in tapetal nuclei, once when the microsporocytes are in zygotene and again during pachytene. Each time the synthetic period was followed by a normal mitosis. Accumulation of RNA in microsporocytes occurred at stages up to late leptotene. After this period, labeled RNA accumulated almost exclusively in their nuclei and at a slower rate than in earlier stages. DNA synthesis, as measured by incorporation of glycine‐C14 and orotic acid‐C14, gave the same results and confirm earlier results with inorganic phosphate‐P32. For RNA, glycine‐C14 and orotic acid‐C14 gave different results. When glycine‐C14 was the source of label, incorporation of C14 in RNA stopped during DNA synthesis in sporogenous cells. Glycine‐C14 was not utilized to a significant extent at any time by tapetal cells for RNA synthesis, but extensively for DNA and protein synthesis. Orotic acid‐C14 was incorporated into RNA of both tapetum and sporogenous cells at various periods in development apparently including the interval of DNA synthesis. Protein synthesis as measured by incorporation of glycine is relatively rapid during premeiotic interphase and leptotene. It continues during the remainder of prophase, but at a much reduced rate. In tapetal cells the rate is rapid in the nuclei during periods of DNA synthesis, but even faster in both cytoplasm and nucleus after divisions are completed and the microsporocytes are in late prophase and division stages. This period of synthesis is perhaps necessary for the postmeiotic functioning of tapetum when it appears to secrete the wall materials for the microspores.
STUDIES OF PALEOZOIC FERNS. THE MORPHOLOGY, ANATOMY, AND TAXONOMY OF ANKYROPTERIS GLABRA
Authors: Eggert Donald A.
Published: January 2018

Eggert, Donald A. (Yale U., New Haven, Conn.) Studies of Paleozoic ferns. The morphology, anatomy, and taxonomy of Ankyropteris glabra. Amer. Jour. Bot. 46(7): 510–520. Illus. 1959.—This is a morphological and taxonomic study of the American specimens of Ankyropteris, with the exception of A. hendricksi, that previous to this time have been referred to A. grayi, originally a Lower Carboniferous species from England, and to A. glabra, a Middle‐Pennsylvanian form from Booneville, Indiana. The problem of the separation of these two closely allied species is discussed, and the original criteria for separation are questioned, on the basis of four specimens described in the present paper. The specimens are from West Mineral, Kans. and Shuler Mine in Iowa. They all have been referred to A. glabra and show extreme plasticity of several features of the plant that is correlated with the size of the stem. The major points of difference between A. glabra and A. grayi are now thought to be the presence of distantly spaced nodes in A. glabra, in contrast to closely spaced ones in A. grayi, and the presence of a small amount of mixed tissue in the stele of A. glabra, compared to a large amount in A. grayi. Well preserved axillary branches were found, whose morphology is typically that of the parent stem. It is suggested that the axillary branches were well developed in the species, and that, therefore, several orders of branching may be present in the American material. Successive orders of branching show diminution and simplification which is interpreted as an expression of the presence of determinate growth in the cauline systems of the plant, an ontogenetic pattern that is not commonly found in living forms.
SALT TOLERANCE WITHIN A TYPHA POPULATION
Authors: McMillan Calvin
Published: January 2018

McMillan, Calvin. (U. Texas, Austin.) Salt tolerance within a Typha population. Amer. Jour. Bot. 46(7): 521–526. Illus. 1959.—Typha in a disturbed salt flat near Lincoln, Nebraska, provided material for an examination of population dynamics. Within the population, clones of T. angustifolia L. tended to occupy the drier sites and those of T. latifolia L. occupied the sites of greater moisture probability. Clones of intermediate morphological characteristics were distributed with both T. angustifolia and T. latifolia. Rhizomes taken from the clones were grown in various NaCl solutions in the greenhouse. Results indicated greatest salt tolerance by T. angustifolia and least salt tolerance by T. latifolia. The intermediate, probably hybrid, clones were intermediate in salt tolerance. Seeds of the 3 clone‐types germinated over the same range of salt concentration. The seeds of all 3 types withstood 4 months submergence in a 2% salt solution and germinated upon being returned to tap water. In the salt flat habitat, the clones of T. latifolia were not vigorous during the years 1956–1957 and many died or were reduced considerably in area of occupancy. The clones of T. angustifolia remained vigorous and flowered over the same period. The intermediate clones were vigorous and increased their coverage, primarily in areas that were occupied prior to 1956 by T. latifolia. The spatial adjustments within the population probably resulted from the selective action of increased salt concentration accompanying the drier conditions of 1956 and 1957.
A STUDY OF MEIOSIS IN HAPLOPAPPUS GRACILIS (COMPOSITAE)
Authors: Jackson R. C.
Published: January 2018

Jackson, R. C. (U. Kansas, Lawrence.) A study of meiosis Haplopappus gracilis (Compositae). Amer. Jour. Bot. 46(7): 550–554. Illus. 1959.—A study of meiosis in the two‐paired Haplopappus gracilis has shown that each pair of chromosomes is easily recognized throughout the various stages of meiosis beginning with pachytene. A comparison of mitotic and meiotic chromosomes has been made, and the data indicate that a conspicuous heteropycnotic knob on chromosome B at pachytene is the nucleolar organizer. Other recognizable chromomeres were observed, but additional study is needed before a cytological map can be drawn to show whether regions other than those described on chromosome A and B may be used as markers.
AUXIN TRANSPORT IN THE LONG SHOOTS OF PINE
Authors: Brown Claud L. , Wetmore Ralph H.
Published: January 2018

Brown, C. L. (Forest Genetics Laboratory, College Station, Texas.), and Ralph H. Wetmore. Auxin transport in the long shoots of pine. Amer. Jour. Bot. 46(8): 586–590. 1959.—Data are presented which show that endogenous auxin in the stem segments of pine is actively transported under extremely low oxygen tension and in amounts equal to that in the normally aerated controls. In distinct contrast, stem segments, previously evacuated of endogenous auxin, which readily transport IAA applied in donor blocks at physiological concentrations in air, do not do so in an atmosphere of pure nitrogen. It is concluded that it is the initial phase, the uptake of IAA from the block into the tissue, which is limiting at low oxygen tension, while the second phase, the transport sensu stricto, is almost independent of oxygen.
CYTOGEOGRAPHY OF PANICUM VIRGATUM IN CENTRAL NORTH AMERICA
Authors: McMillan Calvin , Weiler John
Published: January 2018

McMillan, Calvin. (U. Texas, Austin.), and John Weiler. Cytogeography of Panicum virgatum in central North America. Amer. Jour. Bot. 46(8): 590–593. Illus. 1959.—For 124 clones of Panicum virgatum L. representing 44 local populations from Manitoba and eastern Montana to Texas, the chromosome number was determined. Most of the clones were grown in a transplant garden at Lincoln, Nebraska. Among the earlier‐flowering clones from the northern and western area, a preponderance were tetraploids (n = 18). Among the later‐flowering clones, the Iowa material was predominantly tetraploid, while those from Nebraska presented a diversity of types (n = 18, 27, 36) within each population. A series of polyploids was common in population samples from southern Kansas, Oklahoma, and Missouri. Through the complex breeding patterns resulting from the common occurrence of a range of polyploidy and the possible action of apomixis, variability within the population is maintained, and with it, genetic insurance for survival in highly unpredictable prairie habitats.
THE GENETIC APPROACH TO THE PHYSIOLOGY OF PARASITISM OF THE CORN RUST PATHOGENS
Authors: Dickson J. G. , Syamananda R. , Flangas A. L.
Published: January 2018

Dickson, J. G., R. Syamananda, and A. L. Flangas. (U. Wisconsin, Madison.) The genetic approach to the physiology of parasitism of the corn rust pathogens. Amer. Jour. Bot. 46(8): 614–620. Illus. 1959.—Inbred lines of corn, with known genes conditioning rust reaction to specific clonal and inbred lines of Puccinia sorghi, were used in the study of the physiology of parasitism of the several types of rust reaction. Three different rust reactions incited by 3 lines of the pathogen on the same host and 1 line of the pathogen on several inbred lines of corn, as well as other specific host‐pathogen interactions were investigated. The influence of temperature, light, and carbohydrate on the comparative phenotypic expression of rust reaction for several host‐pathogen genotypes showed differences in response useful for the study of obligate parasitism and the nature of resistance. Both high and low temperatures changed the rust reaction, necrotic fleck, to uredial development and the reverse, for specific genotype combinations. The nature of available carbohydrate (using excised leaves in the absence of photosynthesis) showed little effect on the differential rust reactions, necrotic fleck and uredial development. The comparative rate and total oxygen uptake for leaves of the same host, uninoculated and inoculated with lines of the pathogen inciting the necrotic‐fleck, mesothetic‐X and uredial reactions, respectively, indicated significant differences in physiological response for the 3 reaction types. The necrotic‐fleck reaction showed initially a high oxygen uptake that subsided with the isolation of the obligate parasite by host‐cell necrosis, in contrast to the continuous increase in oxygen uptake in the compatible reaction. The data indicated that in the necrotic‐fleck reaction, the fungus line was initially virulent but nonpathogenic rather than avirulent as indicated commonly in the literature. The results showed also that in corn rust, the compatible and the mesothetic‐X reactions were differentially selective, whereas the necrotic‐fleck was incited uniformly on all resistant host genotypes.
QUANTITATIVE ANALYSIS OF LEAF DEVELOPMENT IN XANTHIUM PENSYLVANICUM
Authors: Maksymowych Roman
Published: January 2018

Maksymowych, Roman. (Villanova U., Villanova, Pa.) Quantitative analysis of leaf development in Xanthium pensylvanicum. Amer. Jour. Bot. 46(9): 635–644. Illus. 1959.—An attempt was made to find a quantitative way of describing the development of the leaf and to correlate the developmental processes, designating precisely their sequence. The processes were presented in terms of the absolute and relative rates of leaf length, expansion of lamina in surface, increase in thickness, rates of cell division of leaf 9 and 13, and tissue differentiation of 3 portions of the lamina. All rates were estimated over the entire period of development, from initiation of a primordium to its maturity. The leaf plastochron index (L.P.I.) was used as a morphological time‐scale. The relative plastochron rates were used for the purpose of correlation of the developmental processes. Leaf 9 elongates exponentially up to 3.0 L.P.I. with an average relative rate (dlnL/dpl) of about 0.78 pl‐1, and it stops growing around 8.0 L.P.I. The lamina stops elongating about 1.5 plastochrons before the petiole. The tip of the lamina expands its surface at a constantly lower relative rate than the middle and the basal portions of the blade. The average relative rate of expansion in area (dlnA/dpl) for the whole lamina is 1.7pl‐1 during the exponential stage. Differentiation of the laminar tissues proceeds basipetally, from the tip toward the base of the leaf. The relative rate of expansion of lamina in thickness (dlnT/dpl) is 0.55 pl‐1 at 1.5 L.P.I. and after 4.0 L.P.I. all cells cease elongating in a plane perpendicular to the leaf surface. The formation of cells proceeds exponentially up to 3.0 L.P.I. and about this time cell divisions stop in all parts of the lamina. The mean relative rate of cell formation (dlnC/dpl) at the exponential phase is 1.41 pl‐1, an increase of about 31% per day. At least 27 generations of cells are involved in the process of leaf formation and the generation time was calculated to be 0.5 plastochron or 2.2 days.
DEVELOPMENT OF THE OVULE AND MEGAGAMETOPHYTE IN SAXIFRAGA HIERACIFOLIA
Authors: Wiggins Ira L.
Published: January 2018

Wiggins, Ira L. (Stanford U., Stanford, Calif.) Development of the ovule and megagametophyte in Saxifraga hieracifolia. Amer. Jour. Bot. 46(10): 692–697. Illus. 1059.—Buds of Saxifraga hieracifolia collected in the vicinity of Point Barrow, Alaska, fixed, sectioned, and stained by standard methods, revealed that the archesporial cell in the ovule of this species is hypodermal and gives rise to the megaspore mother cell and a small number of parietal cells. Occasionally 2 megaspore mother cells occur within an ovule. Meiosis in the megaspore mother cell produces a linear tetrad of megaspores, the chalazal one of which normally gives rise to a monosporic, Polygonum‐type megagametophyte. The polar nuclei fuse near the chalazal end of the megagametophyte and the antipodal cells disintegrate prior to fertilization. A distinct filiform apparatus and a marked lateral “spur” develop on each synergid. Vacuolation in the egg cell and in the synergids follows the usual pattern. Only a single integument surrounds the nucellus.
A NEW METHOD FOR THE DETERMINATION OF OSMOTIC PRESSURE
Authors: Lockhart James A.
Published: January 2018

Lockhart, James A. (California Inst. Tech., Pasadena.) A new method for the determination of osmotic pressure. Amer. Jour. Bot. 46(10): 704–708. Illus. 1959.—A new method for the determination of osmotic pressure in appropriate plant tissues is described. This method is based on the observation that the degree of deformability of tissue equilibrated in hypertonic solution is a linear function of the extent by which the external osmotic pressure exceeds the osmotic pressure of the cell contents. Extrapolation of the deformability vs. external osmotic pressure to zero deformation yields, then, the osmotic pressure of the tissue at limiting plasmolysis. It is shown that the osmotic pressure determinations are independent of incubation time and magnitude of applied force. A simple device is described for measuring bending throughout a wide range of angles, while keeping the applied force constant.
SEEDLING GROWTH STUDIES OF EARLY‐RIPENING PEACHES. I. INTERRELATIONSHIP BETWEEN EMBRYO MATURITY, GROWTH SUBSTANCES AND SEEDLING GROWTH
Authors: Weaver Gerald M. , Hough L. Fredric
Published: January 2018

Weaver, Gerald M., and L. Fredric Hough. (Rutgers, The State Univ., New Brunswick, N. J.) Seedling growth studies of early‐ripening peaches. I. Interrelationship between embryo maturity, growth substances and seedling growth. Amer. Jour. Bot. 46(10): 718–724. Illus. 1959.—Peach fruits of ‘Raritan Rose’ were harvested 75, 83, 91, 99 and 107 days after full bloom. Embryos were excised, and cultured on artificial media. Growth responses following 8 wk. cold treatment varied considerably with embryo maturity. No correlation existed between seedling survival and the initial responses of shoots. Root growth of 83‐day embryos exceeded that of all other stages of maturity. This was reflected in maximum seedling survival and vigor. Initial shoot growth was greatest from embryos harvested at 91 days and at maturity (107 days), but all shoots developed into rosettes which may expand slightly or develop normally from axillary buds. Bioassays of growth substances suggest a strong correlation between early shoot development and auxin concentration. Root growth‐responses appeared to be correlated with a promotor‐inhibitor balance. The results of wheat coleoptile assays of embryo extracts chromatographed in an isopropanol: ammonia: water solvent (8:1:1) suggest the presence of three growth promotors, in greatest concentration at Rf 0.70, but also at Rf values 0.10 and 0.30. Two growth inhibitors were present in embryo tissue at Rf values 0.27 and 0.96, the former decreasing in concentration with increasing embryo maturity.
THE ENZYMATIC MACERATION OF PLANT TISSUES: OBSERVATIONS USING A NEW METHOD OF MEASUREMENT
Authors: McClendon John H. , Somers G. Fred
Published: January 2018

McClendon, J. H., and G. F. Somers. (U. Delaware, Newark.) The enzymatic maceration of plant tissues: observations using a new method of measurement. Amer. Jour. Bot. 47(1) :1‐7. Illus. 1960.—An apparatus is described for measuring the breaking strength of tissue slices. The apparatus was used in the measurement of maceration of potato tuber slices by fungal and tomato enzymes. During the enzymatic maceration of the slices, the strength fell in an approximately logarithmic manner to a stable value less than 5% of the initial strength. Calcium ion did not prevent enzymatic maceration, although it increased the strength of the tissue. Chelating agents used alone did not macerate but facilitated the enzymatic maceration. There was a pH optimum at 3.0—3.5 with a commercial “Pectinase” and enzymes from Botryosphaeria ribis but near 4.7 for a preparation from tomato fruit. The reciprocal of the time for a set strength reduction was proportional to the square root of the enzyme concentration. The relative strength remaining [(initial strength/final strength)–1] after an arbitrary reaction time was proportional to the enzyme concentration raised to the 0.8 power. The temperature coefficient was about 2.5, but other evidence indicated some limitation by diffusion. Non‐enzymatic maceration increased rapidly below pH 3 and was especially prominent after subsequent neutralization.
CATABOLISM OF C14‐LABELLED GLUCOSE, GLUCONATE AND ACETATE IN VERTICILLIUM ALBO‐ATRUM
Authors: Brandt W. H. , Wang C. H.
Published: January 2018

Brandt, W. H., and C. H. Wang. (Oregon State College, Corvallis.) Catabolism of C14‐labelled glucose, gluconate and acetate in Vertieillium albo‐atrum. Amer. Jour. Bot. 47(1): 50—53. Illus. 1960.–The major catabolic pathways of glucose in conidia from rapidly proliferating shake‐cultures of Verticillium albo‐atrum Reinke and Berth, isolated from okra and cultured under light at 25°C. have been identified and estimated from data obtained by the radiorespirometric method. When pure oxygen was used as a sweep gas, glucose appeared to be catabolized approximately 60% via the Embden‐Meyerhof‐Parnas glycolysis (EMP) and 40% via phosphogluconate decarboxylation (PGD). With air as the sweep gas, about 48% of the glucose was catabolized via the EMP pathway and about 52% via the PGD pathway. Glucose was catabolized under a pure nitrogen atmosphere, but there was little PGD, operating under these conditions. Gluconate was rapidly decarboxylated in the C‐l position, but only a small proportion of carbon atoms from other positions appeared in the respiratory CO2. Acetate was utilized readily in such a way that the operation of the tri‐carboxylic acid cycle may be inferred. Pyruvate was used slowly because it appeared to enter the conidia slowly.
STUDIES ON DIPLOID STRAINS OF DICTYOSTELIUM DISCOIDEUM
Authors: Ross Ian K.
Published: January 2018

Ross, Ian K. (Yale U., New Haven, Conn.) Studies on diploid strains of Dictyostelium discoideum. Amer. Jour. Bot. 47 (1) : 54—59. Illus. 1960.–Three strains of Dictyostelium discoideum having the diploid number of chromosomes (14) at all stages of their life cycle were examined. No evidence of sexuality as shown by syngamy or meiosis was found in the diploid strains. Two of the diploid strains were unstable and reverted to the haploid type with 7 chromosomes. These haploid strains had a sexual phase in which syngamy and meiosis were observed. The nuclear behavior of both the diploid and haploid strains differed from that reported in previous papers.
NUCLEAR STRUCTURE AND DIVISION IN THE VEGETATIVE MYCELIUM OF THE SAPROLEGNIACEAE
Authors: Bakerspigel Alexander
Published: January 2018

Bakerspigel, Alexander. (The New Mount Sinai Hospital, Toronto.) Nuclear structure and division in the vegetative mycelium of the Saprolegniaceae. Amer. Jour. Bot. 47(2): 94—100. Illus. 1960.–Saprolegnia parasitica, S. ferax and Achlya racemosa are additional examples of fungi in whose vegetative mycelium the nuclei do not divide in a manner directly comparable to ordinary mitosis. During division the entire nucleus, which consists of a crescent, ring or cap of chromatin and the nucleolus, becomes angular and elongates. The chromatin separates into 2 portions which are situated at opposite ends of the elongating nucleus. As division proceeds the elongated nucleus constricts at the midregion and the sister nuclei separate. Each sister nucleus consists of a crescent of chromatin and a portion of the divided nucleolus. Spindles, chromosomal filaments or metaphase plates could not be demonstrated during division.
THE GROWTH OF THE STEM TIP OF KALANCHOËU CV. ‘BRILLIANT STAR’
Authors: Stein Diana B. , Stein Otto L.
Published: January 2018

Stein, Diana B. and o. L. Stein. (Montana State U., Missoula.) The growth of the stem tip of Kalanchoë cv. ‘Brilliant Star.‘ Amer. Jour. Bot. 47 (2) : 132—140. Illus. I960.–The purposes of this investigation were (1) to define as clearly as possible the events in the shoot apex and its immediate derivatives during the ontogeny of the shoot; and (2) to determine the changes which occur during the transition from a vegetative to a reproductive meristem. Rate of leaf production in Kalanchoë is basically constant. The rate of leaf growth subsequent to the early primordial state is, however, dependent on the age of the plant and on the environment in which the plant is grown. By keeping these factors constant a correlation can be demonstrated between the size of the youngest visible leaf and the microscopic primordia. Throughout its ontogeny the general architecture of the shoot apex remains essentially the same. Two tunica layers cover the corpus in the vegetative shoot apex, and even in the flowering meristem these 2 layers can be detected. The apex is essentially flat and blends into the adjacent leaf primordia early in the plastochron. About 10 days after flower induction has been started the apex changes its form to a dome, primarily by increased cell division. At the same time the rate of elongation of the youngest internodes increases thus placing the flowering stem tip atop an elongated stem. Axillary development is ultimately responsible for the development of a dichasium.
THE COMPARATIVE MORPHOLOGY AND RELATIONSHIPS OF THE MAGNOLIACEAE. III. CARPELS
Authors: Canright James E.
Published: January 2018

Canright, James E. (Indiana U., Bloomington.) The comparative morphology and relationships of the Magnoliaceae. III. Carpels. Amer. Jour. Bot. 47(2): 145—155. Illus. 1960.–The morphology and vascular anatomy of the carpels of 49 species in 9 of the 10 genera of the Magnoliaceae are described. Assuming that the conduplicate carpel of Australasian species of Drimys (Winteraceae) represents the primitive condition, various carpellary modifications are indicated for the Magnoliaceae. These evolutionary spcializations from the basic type include: basal adnation, lateral concrescence, reduction in number of ovules, closure of the ventral suture, and localization of stigmatic areas. Among the examined species it was determined that carpels of the genera Elmerrillia and Manglietia retain the most primitive features, whereas those of the genus Liriodendron possess the most advanced. Comparisons are made with the gynoecia of related ranalean families, viz., Himantandraceae, Degeneriaceae and Annonaceae.
A NEW ASPECT OF CORTICAL DEVELOPMENT IN ROOTS
Authors: Heimsch Charles
Published: January 2018

Heimsch, Charles. (Miami U., Oxford, Ohio.) A new aspect of cortical development in roots. Amer. Jour. Bot. 47(3) : 195—201. Illus. I960.–Excised roots of some tomato varieties exhibit a pronounced increase in diameter of the apex when grown in culture. Anatomical study demonstrated that most diameter growth was attributable to an increase in cell number across the cortex, this having resulted from a progressive increase in the number of periclinal divisions in the innermost cortical cell layer. Although these divisions occur within 200 microns or less of the root apex, their differential distribution during development can be inferred from the cell pattern at mature levels in the basal portion of the tip. Nearly all roots showed an unequal distribution of the last periclinal divisions, there being at some levels more in sectors peripheral to phloem strands than elsewhere. Toward the tip from such levels the sectors of widened cortex were extended around the central cylinder, in some cases around the xylem poles to complete a layer, of newly added cells. The findings are discussed in relation to developmental implications and interpretations and possible causal factors are reviewed.
CHROMOSOMES AND CROSSING BEHAVIOR OF SOME SPECIES OF SANSEVIERIA
Authors: Menzel Margaret Y. , Pate James B.
Published: January 2018

Menzel, Margaret Y. (Florida State U., Tallahassee), and James B. Pate. Chromosomes and crossing behavior of some species of Sansevieria. Amer. Jour. Bot. 47(3) : 230—238. Illus. 1960.–Approximately 20 species (28 clones) studied were diploids, tetraploids or hexaploids of the basic numbers x = 20; about 40% of the taxa were polyploid. All species had similar karyotypes, except for chromosome number. Five of 12 combinations of diploid species gave fertile F1 hybrids; 4 studied cytologically showed 20 bivalents at metaphase I. Two triploid interspecific hybrids showed high trivalent frequencies. In contrast, multivalent formation in polyploid species was variable but rather low. Morphological relationships appeared reticulate among and between diploids and polyploids and did not coincide with barriers to crossing or to hybrid fertility. The following tentative hypothesis concerning relationships in the genus is proposed: Sansevieria is monophyletic and speciation has proceeded through genetic variation and hybridization at the diploid level and by allopolyploidy (of the segmental type) ; a low level of chromosome differentiation has accompanied speciation such that complete pairing occurs in diploid hybrids, but considerable preferential pairing occurs in allopolyploids. The occurrence of both polyploid and hybrid vigor, the fertility of hybrids between species differing greatly in morphology and physiology, and the high potential for vegetative propagation make the genus a favorable subject for breeding based on interspecific hybridization.
ABSORPTION OF HERBICIDES BY ROOTS
Authors: Crafts A. S. , Yamaguchi S.
Published: January 2018

Crafts, A. S., and S. Yamaguchi. (U. California, Davis.) Absorption of herbicides by roots. Amer. Jour. Bot. 47(4): 248—255. Illus. 1960.—Many herbicides are used through soil. When 2,4‐D*2 was applied to culture‐solution barley, bean, cotton, and Zebrina plants, there was evidence that the herbicide is held at high concentration by the roots. Very little of the labeled compound moved into the tops of barley, Zebrina and bean; a fair quantity was found in cotton foliage. Barley seedlings allowed to absorb 2,4‐D*, ATA*, MH*, urea*, monuron*, dalapon*, simazin*, P32 and IAA* showed interesting differences. All chemicals were highly sorbed by roots, 2,4‐D* was moved to tops in least amount, urea was next; the other seven were moved in larger quantities. ATA*, MH*, IAA*, P32, and dalapon* seemed readily phloem mobile; monuron* and simazin* seemed limited to xylem movement. Results are discussed in relation to the mechanism of root uptake.
REVERSION FROM FLOWERING TO THE VEGETATIVE STATE IN XANTHIUM
Authors: Lam S. L. , Leopold A. C.
Published: January 2018

Lam, S. L. and A. C. Leopold. (Purdue U., Lafayette, Indiana.) Reversion from flowering to the vegetative state in Xanthium. Amer. Jour. Bot. 47(4): 256—259. Illus. 1960.–Plants of Xanthium pensylvanicum Wallr. which had been induced with short photoperiods were caused to revert to the vegetative state either by decapitation or by pinching and subsequent partial de‐budding. The ability of induced plants to revert varies with the intensity of the inductive stimulus, and with the extent to which the plant is cut back. Four successive decapitation treatments caused complete reversion of almost all plants which had been given 7 inductive cycles. Reversion can be obtained after 3 inductive cycles even when all of the induced leaves remain on the plant. It is suggested that under the conditions of these experiments the synthesis of the flowering stimulus is stopped or the stimulus is immobilized in the leaves and made ineffective.
SHOOT HISTOGENESIS: SUBAPICAL MERISTEMATIC ACTIVITY IN A CAULESCENT PLANT AND THE ACTION OF GIBBERELLIC ACID AND AMO‐1618
Authors: Sachs R. M. , Lang A. , Bretz C. F. , Roach Joan
Published: January 2018

Sachs, R. M., A. Lang, C. F. Bretz and Joan Roach. (U. California, Los Angeles.) Shoot histogenesis: subapical meristematic activity in a caulescent plant and the action of gibberellic acid and Amo—1618. Amer. Jour. Bot. 47(4): 260—266. Illus. 1960.–Studies on gibbereilininduced stem formation in rosette plants (Sachs et al., 1959) have shown that a zone of intensive meristematic activity, arising below the existing apical meristem, is almost solely responsible for stem histogenesis, i.e., the formation of the cells constituting the elongate stem. An extensive subapical zone of meristematic activity is also present in caulescent plants, such as Chrysanthemum morifolium, Amo‐1618 ([4‐hydroxy‐5 isopropyl‐2 methylphenyl] trimethylammonium chloride, 1‐piperidine carboxylate) completely inhibits subapical meristematic activity in chrysanthemum, causing the plants to assume a dwarfed, rosette‐like habit of growth. Gibberellic acid, applied either simultaneously, or following the Amo—1618 treatment, completely prevents or reverses the effect of Amo—1618, making the plants retain or resume their normal growth habit. Amo—1618 and gibberellic acid have relatively little effect upon the activity of the apical meristem of Chrysanthemum. Thus, while the apical meristem proper (eu‐ or promeristem) is the site of shoot organization and the ultimate source of the cells of the entire shoot, the subapical zone of division, termed the subapical meristem, is largely responsible for stem histogenesis in caulescent as well as in rosette plants. Gibberellins, or native, gibberellin‐like substances appear to regulate the activity of the subapical meristem and thus to play an important role in shoot development. Amo—1618 and related compounds seem to exert their dwarfing effect in plants by acting as antagonists of gibberellins, at least with respect to the latters' function in regulating the subapical meristematic activity in the shoot.
ONTOGENY OF THE FLORAL APEX OF MICHELIA FUSCATA
Authors: Tucker Shirley C.
Published: January 2018

Tucker, Shirley C. (u. Minnesota, Minneapolis.) Ontogeny of the floral apex of Michelia fuscata. Amer. Jour. Bot. 47(4): 266—277. Illus. 1960.–The floral apex of Michelia fuscata, although determinate, has a prolonged period of activity. It undergoes an increase in average height and diameter through the time of initiation of stamens, followed by a decrease in average size during initiation of successive carpels. The floral apex also shows periodic or plastochronic fluctuation in size and configuration between initiation of tiers of appendages at nearly the same level and time. Plastochrons of different duration alternate in an orderly sequence in the floral meristem.
THE MORPHOLOGY AND ANATOMY OF CALLIPTERIDIUM SULLIVANTI
Authors: Leisman Gilbert A.
Published: January 2018

Leisman, Gilbert A. (Kansas State Teachers Coll., Emporia.) The morphology and anatomy of Callipteridium Sullivanti. Amer. Jour. Bot. 47(4) : 281—287. Illus. 1960.–Previously undescribed pinnules of Callipteridium Sullivanti (Lesq.) Weiss have been studied in Iowa and Kansas coal balls. Conventional peel techniques revealed the anatomy while deliberately fracturing the coal ball revealed morphological features. Epidermal studies were also conducted after macerating small portions of the coal ball. Evidence indicates that these pinnules were borne on Myeloxylon petioles. Arguments are advanced for removing this species from the genus Alethopteris and returning it to Callipteridium.
ADAPTATION IN PANTOTHENATE‐REQUIRING NEUROSPORA. I. A GENE MODIFYING PANTOTHENATE MUTANTS
Authors: Davis Rowland H.
Published: January 2018

Davis, r. H. (California Inst. Tech., Pasadena.) Adaptation in pantothenate‐requiring Neurospora. i. a gene modifying pantothenate mutants. Amer. Jour. Bot. 4(5): 351–357. Illus. 1960.—a modified pantothenicless strain was isolated from a pan‐1, al‐1, A mycelium which had adapted to a limiting concentration of pantothenate. The modified and original strains differ by a single gene, m, which is not linked genetically to either of the 2 known pantothenic acid loci. The gene m appears to modify the uptake, rather than the synthesis, of pantothenate on the part of both pan‐1 and pan‐2 mutants. Neither pan mutant in combination with m grows on minimal medium. However, the pan‐1 m and pan‐2 m strains grow to a greater extent than pan‐1 or pan‐2 in limiting pantothenate concentrations. The mechanism of action of the m gene is discussed, and compared to modifiers of certain other mutant phenotypes of Neurospora.
GROWTH AND ORGANIZED DEVELOPMENT OF CULTURED CELLS IV. THE BEHAVIOR OF THE NUCLEUS
Authors: Mitra J. , Mapes Marion O. , Steward F. C.
Published: January 2018

Mitra, J., Marion O. Mapes, and F. C. Steward. (Cornell U., Ithaca, New York.) Growth and organized development of cultured cells. IV. The behavior of the nucleus. Amer. Jour. Bot. 47(5) : 357—368. Illus. 1960.–The nuclei and the chromosomes of carrot cells have been examined at various stages throughout the following sequence: (1) growth of a tissue culture from a preformed explant of secondary phloem from the carrot root; (2) growth and multiplication of carrot cells freely suspended in a liquid medium; (3) growth and re‐formation of organs (roots) and whole plants (including flowers) from cells in the freely suspended state. The cells of the carrot are normally diploid (2n = 18), the cells which develop in the explant are also diploid, and the cells of the re‐formed organs, and even the flowers developed upon plants grown from cells, are also normal and diploid; normal meioses also occur. Nevertheless, the wide range in growth and form of the freely suspended cells is accompanied by a rich diversity of cytological conditions; these include tetraploid and highly polyploid nuclei which divide, haploidy and such chromosomal aberrations as di‐ and even tri‐centric bridges. Two division figures showing chromosome numbers at different levels of ploidy were seen within the confines of one large cell, and, in another, 2 adjacent division figures were observed with chromosome numbers lower than diploid. Small thick‐walled, densely protoplasmic cells divide to form bi‐ and tetra‐nucleate conditions, and in a giant cell a highly multinucleate condition has been seen. Despite this, however, all the regenerated roots and plants yet examined are normally diploid. The implications of these events are discussed.
INFECTION POTENTIAL AND GROWTH OF LAGENIDIUM CHTHAMALOPHILUM
Authors: Johnson T. W.
Published: January 2018

Johnson, T. W., Jr. (Duke U., Durham, N. C.) Infection potential and growth of Lagenidium chthamalophilum. Amer. Jour. Bot. 47(5): 383—385. Illus. 1960.–Temperature and salinity influence infection of Chthamalus fragilis and Balanus amphitrite denticulata ova by Lagenidium chthamalophilum. Optimum conditions for infection are 20—22°C. in raw (as opposed to aged) sea water of 34 0/00 salinity. With increases in incubation temperature, the percentage of infection occurring in egg lamellae submerged in hypersaline waters also increases. Nutrition has essentially the same effect on salinity tolerance as water temperature: only on enriched agar media will L. chthamalophilum grow vegetatively at salinities well above that of normal sea water. Ova of B. amphitrite denticulata become infected by L. chthamalophilum only at a temperature of 15°C. in hypersaline water, or if the Balanus ova are subjected to below‐freezing temperatures before exposure to the fungus.
PEROXIDASE DISTRIBUTION IN THE LEADERS OF ERECT AND INCLINED PINUS STROBUS SEEDLINGS
Authors: Westing Arthur H.
Published: January 2018

Westing, A. H. (Purdue U., Lafayette, Indiana.) Peroxidase distribution in the leaders of erect and inclined Pinus strobus seedlings. Amer. Jour. Bot. 47(8) : 609–612. 1960.—A longitudinal gradient of peroxidase activity, decreasing basipetally, which was independent of stem inclination, was found in the leaders of Pinus strobus L. Inclination of intact leaders also had no effect on the transverse distribution of peroxidase activity, but when such leaders were decapitated and defoliated a transverse gradient, increasing from upper side to lower, did develop. Applications of α‐naphthaleneacetic acid prevented this transverse redistribution from occurring. Mutilation also resulted in an increase of the overall level of peroxidase activity in the leaders.
CHROMOSOME DIFFERENTIATION IN SEVERAL SPECIES OF MELILOTUS
Authors: Shastry S. V. S. , Smith W. K. , Cooper D. C.
Published: January 2018

Shastry, Sishta V. S., William K. Smith, and Delmer C. Cooper. (U. Wisconsin, Madison.) Chromosome differentiation in several species of Melilotus. Amer. Jour. Bot. 47(8) : 613–621. Illus. 1960.—Two species of the section Eumelilotus (M. alba and M. officinalis), 2 of Micromelilotus (M. messanensis and M. segetalis), 2 F1 hybrids (M. officinalis × M. alba and M. messanensis × M. segetalis), 2 autotetraploids (M. alba and M. officinalis), and 1 allotetraploid (M. officinalis × M. alba), were utilized during the course of this investigation. The 4 species and F1 hybrids have 16 somatic chromosomes and the tetraploids have twice that number (32). The 2 Eumelilotus species are completely isolated because of seed failure after cross pollination. The F1 hybrid (M. officinalis × M. alba), obtained elsewhere by the use of embryo‐culture techniques, was intermediate between the parents in certain morphological characters and was ca. 75% pollenfertile whereas the parents approached complete fertility. No structural differences between the chromosomes were evident at pachytene. Disturbances which led to the reduced fertility occurred at later stages of meiosis. The Micromelilotus species are cross compatible, but the F1 hybrid (M. messanensis × M. segetalis) is highly sterile. Despite chromosome structural differences of various types evident at pachytene, bivalents regularly occur at metaphase I. Irregular distribution of the chromosomes at later stages of meiosis leads to high sterility. Species which readily cross but produce a hybrid of very low fertility are likely to compound chromosomal structural differences, because of abnormalities in meiosis, in contrast with species that are completely incompatible.
STUDIES IN THE HELMINTHOCLADIACEAE. II. TRICHOGLOEOPSIS
Authors: Abbott Isabella A. , Doty Maxwell S.
Published: January 2018

Abbott, Isabella A. (Hopkins Marine Station of Stanford U., Pacific Grove, Calif.), and Maxwell S. Doty. Studies in the Helminthocladiaceae. II. Trichogloeopsis. Amer. Jour. Bot. 47(8) : 632–640. Illus. 1960.—A new genus, Trichogloeopsis, in the Helminthocladiaceae of the red algal order Nemalionales is described. Its diagnostic features are the possession of sterile rhizoids produced by the gonimoblast, and the fact that the carpogonial branch is a modified vegetative filament. The type species of the genus is T. hawaiiana from the Hawaiian Islands. Two species of Liagora, L. pedicellata from the Bahamas and L. mucosissima from the Ryukyus, are transferred to the new genus.