bluuebunny/crossref_metadata_2025 huggingface dataset:
RELATION OF DWARFMISTLETOE (ARCEUTHOBIUM) TO THE XYLEM TISSUE OF CONIFERS. I. ANATOMY OF PARASITE SINKERS AND THEIR CONNECTION WITH HOST XYLEM
Authors: Srivastava L. M. , Esau K.
Published: January 2018

Srivastava, L. M., and K. Esau. (U. California, Davis.) Relation of dwarf mistletoe (Arceuthobium) to the xylem tissue of conifers. I. Anatomy of parasite sinkers and their connection with host xylem. Amer. Jour. Bot. 48(2): 159–167. Illus. 1961.—The anatomy of the sinkers of Arceuthobium infecting 7 species of conifers was studied by the use of serial cross, radial, and tangential sections of the host wood. The sinkers were found to be composed of parenchyma cells only, or of parenchyma cells and tracheary elements, including vessel elements. In all species tracheary cells of the sinkers had direct contacts with the host tracheids of axial and radial systems. Typically the sinkers were associated with rays of the host wood. In some species, the centripetal ends of sinkers were wedged in radially among the axial tracheids of the host, but centrifugally such sinkers were usually found associated with rays. In the region of the host cambium the sinker contained parenchyma cells meristematic in appearance and, in 6 out of 7 species, also mature tracheary elements. The oldest of these elements became stretched and ruptured, a circumstance indicating that growth occurred in the part of the sinker embedded in the host cambium. This growth appeared to be coordinated with that of the host cambium, so that the sinker became embedded in the host xylem and phloem. Radial centripetal penetration of sinkers among differentiating axial tracheids of the host possibly occurred to a limited extent.
A RECORD OF PAULOWNIA IN THE TERTIARY OF NORTH AMERICA
Authors: Smiley Charles J.
Published: January 2018

Smiley, Charles J. (Macalester Coll., St. Paul, Minn.) A record of Paulownia in the Tertiary of North America. Amer. Jour. Bot. 48(2): 175–179. Illus. 1961.—Paulownia, an eastern Asiatic genus in the family Scrophulariaceae, has been identified from fossil leaves in the Ellensburg flora of Washington. Age of these fossils is late Miocene (Barstovian) to early Pliocene (Clarendonian). They are nearly identical to leaves of the living P. tomentosa (Thunberg) Steudel, a deciduous tree now growing in temperate parts of China and one that has escaped from cultivation in eastern United States. Identification is based on comparative leaf morphology. Modern and fossil Paulownia leaves may be distinguished from those of such other genera as Buettneria, Catalpa, and Cercis by secondary and tertiary venation. Central Washington environment during this time was well suited to the growth and reproduction of Paulownia, judging from such fossil associates as Liquidambar, Nyssa, Passiflora, Persea, Rhododendron, Ulmus, and Zelkova. Deciduous habit, present temperate environment, possible early Tertiary record in Alaska, later Tertiary records in middle latitudes of North America and Europe, and present occurrence in China indicate that Paulownia was once widely distributed over the northern hemisphere. Secular climatic trends toward cooler conditions since the Eocene appear to have resulted in the southward migration of Paulownia as a member of the Arcto‐Tertiary Geoflora. Subsequent extinctions in Europe and North America may have resulted from Pleistocene glacial climates, and from barriers to further migrations to more southern latitudes.
THE EFFECTS OF SELECTED ANTIBIOTICS ON PURE CULTURES OF ALGAE
Authors: Hunter Edward O. , McVeigh Ilda
Published: January 2018

Hunter, E. O., Jr., and Ilda McVeigh. (Vanderbilt U., Nashville, Tenn.) The effects of selected antibiotics on pure cultures of algae. Amer. Jour. Bot. 48(2): 179–185. 1961.—A determination was made of the effectiveness of various concentrations of actidione, nystatin, amphotericin‐A, anisomycin, and sulfocidin, antibiotics active primarily against fungi, in inhibiting representative species of Myxophyceae, Chlorophyceae, Bacillariophyceae, Xanthophyceae, and Euglenophyceae. Similar investigations were made using polymyxin‐B sulfate and bacitracin, antibiotics inhibitory to certain groups of bacteria. Concentrations of 1, 2, 20, 50, 100, and 200 p.p.m. were used. Concentrations of 200 p.p.m. or less of anisomycin, nystatin and actidione had little or no detectable effect on the Myxophyceae but were toxic to members of the Chlorophyceae and the Bacillariophyceae. Thus, these 3 antibiotics are of potential value in eliminating green algal and diatom contaminants from cultures of blue‐green algae. Since bacitracin was found to be inhibitory to members of the Myxophyceae at concentrations not toxic to representatives of the other groups tested, it may prove useful in eradicating blue‐green algae from cultures of other forms. Microscopic examinations indicated that the cells of cultures of species belonging to the Chlorophyceae, the Myxophyceae, and the Euglenophyceae, when exposed to antibiotics to which they were sensitive, usually underwent lysis, while those of species of Xanthophyceae and of Bacillariophyceae generally showed a loss in pigmentation.
BIOTIC RELATIONSHIPS BETWEEN SOIL ALGAE AND OTHER MICROORGANISMS
Authors: Parker Bruce C. , Bold Harold C.
Published: January 2018

Parker, Bruce C., and Harold C. Bold. (U. Texas, Austin.) Biotic relationships between soil algae and other microorganisms. Amer. Jour. Bot. 48(2): 185–197. Illus. 1961.—A study was conducted of biotic relationships between various algae and other microorganisms isolated from a sample of Texas soil. From 143 two‐membered combinations of organisms tested in soil‐water cultures, 3 were selected for detailed studies of the nature of the causal mechanisms of the associative effects. These were: (1) an association between a species of Bracteacoccus (Br. A‐20) and a heterotrophic bacterium (B‐6); (2) an association between a species of Chlamydomonas (Ch. 10) and a species of Streptomyces (Act‐1); and (3) an association between a blue‐green alga, Phormidium sp. (Ph. 14), and an as‐yet‐unidentified fungus (F‐2). In the first association, the heterotrophic bacterium increased growth of Bracteacoccus up to 20 times in soil‐water culture; the chief cause of stimulation was shown by a series of experiments to be the decomposition by the bacterium of complex nitrogenous substrates in the soil resulting in the release of simplified products which were available to the alga as a nitrogen source. In soil‐water culture, Streptomyces (Act‐1) enhanced the growth and motility of Chlamydomonas (Ch. 10) and induced akinetogenesis in the alga, while the actinomycete itself was stimulated in growth and production of conidia. The mutual stimulation was shown to be caused, in part, by carbon dioxide‐oxygen interchange between the organisms. Motility of Ch. 10 was enhanced by a decrease in nitrogen as a result of the growth of Act‐1 and by the ability of Act‐1 to decompose and assimilate the extracellular polysaccharide of the alga. The assimilation of the extracellular polysaccharide by the actinomycete promoted its growth and conidia production. Initiation of akinetogenesis in Chlamydomonas occurred exclusively in close association with the filaments of Streptomyces in soil‐water cultures, and only when the concentration of available nitrogen dropped below a critical level. The akinetogenic factor has not yielded to isolation and identification, but there is some suggestion that it may be an antibiotic substance. Phormidium (Ph. 14) was frequently antagonized and annihilated by fungus 2 in the soil‐water medium. Attempts to extract growth inhibitors from filtrates of the fungal medium were unsuccessful. Indirect evidence suggested that perhaps the consumption of extracellular polysaccharide with concomitant release of organic acid by the fungus might be the factor inhibiting growth of Phormidium. Attempts to confirm experimentally the ecological significance for these biotic relationships are reported.
STUDIES IN THE QUERCUS UNDULATA COMPLEX I. A PRELIMINARY STATEMENT
Authors: Tucker John M.
Published: January 2018

Tucker, John M. (U. California, Davis.) Studies in the Quercus undulata complex. I. A preliminary statement. Amer. Jour. Bot. 48(3): 202–208. Illus. 1961.—The taxonomic history of Quercus undulata, a highly variable, problematic complex of the Southwest, is discussed. Conservatively treated as a single species, it comprises a wide range of forms which at one extreme approach Q. gambelii morphologically, and, at the other, Q. grisea, Q. turbinella, and other species. The postulate was made that Q. undulata had arisen through hybridization between these very different oaks. Field observations and preliminary study of numerous population samples confirm this postulate. (Detailed morphological analyses are in progress.) Seven species have apparently been involved—Q. gambelii (the “common denominator” of the complex) has hybridized in different parts of its range with one or another of the following: Q. arizonica, Q. turbinella, Q. havardii, Q. muehlenbergii, Q. mohriana, and Q. grisea. The latter 6 species are discussed individually, and the extent to which each contributes to the complex, and the area in which this occurs, are indicated.
CHROMOSOME NUMBERS IN THE COMPOSITAE. IV. NORTH AMERICAN SPECIES, WITH PHYLETIC INTERPRETATIONS
Authors: Turner B. L. , Ellison W. L. , King R. M.
Published: January 2018

Turner, B. L., W. L. Ellison, and R. M. King. (U. Texas, Austin.) Chromosome numbers in the Compositae. IV. North American species, with phyletic interpretations. Amer. Jour. Bot. 48(3): 216–223. Illus. 1961.—Chromosome counts from 116 different plant populations representing 75 taxa (72 species in 39 genera) are reported. These include the first species counts for the following genera: Actinospermum (x = 19), Baltimora (x =15), Calea (x = ca. 17, 18), Calyptocarpus (x = 12), Hecubaea (x = 17), Lagascea (x = 17), Schistocarpha (x = 8), Melanthera (x = 15), Pectis (x = 12), Perymenium (x = 15), Sanvitalia (x = 8), and Trigonospermum (x = 15). Chromosome counts for Chrysopsis trichophylla (n = 5), Cirsium horridulum (n = 16), Hidalgoa ternata (n = 16,) Tridax balbisioides (n = 10), Tridax trilobata (n = 10), and Verbesina crocata (n =18) differ from the reported basic numbers as determined from other species in these genera. Taxa closely related to Tridax procumbens were found to have the diploid number n = 9, thus establishing the polyploid nature (n = 18) of this widespread polymorphic species. When appropriate, the chromosomal information has been related to systematic problems.
PROBABILITY OF DIVISION OF CELLS IN THE EPIDERMIS OF THE PHLEUM ROOT
Authors: Erickson Ralph O.
Published: January 2018

Erickson, Ralph O. (U. Pennsylvania, Philadelphia.) Probability of division of cells in the epidermis of the Phleum root. Amer. Jour. Bot. 48(3): 268–274. Illus. 1961.—Photomicrographic records of the growth of a Phleum root, made at R. H. Goodwin's laboratory, in which individual epidermal cells can be identified, have been analyzed to provide estimates of the probability that cells at various distances from the apex will divide. In the apical part of the meristem, from 0μ to about 100μ from the apex, all cells divide (prob. = 1.0). From about 100μ to 275μ, the probability of division falls progressively to 0.0. The relationship of these estimates to rates of cell division and elongation in the same root is discussed.
STUDIES OF TWO POLYCENTRIC CHYTRIDS IN PURE CULTURE
Authors: Goldstein Solomon
Published: January 2018

Goldstein, Solomon. (Yale U., New Haven, Conn.) Studies of two polycentric chytrids in pure culture. Amer. Jour. Bot. 48(4): 294–298. Illus. 1961.—A study was made of some of the chemical and physical factors affecting the growth of Nowakowskiella elegans Schroeter and N. ramosa Butler in pure culture. Maximal harvests of the former were obtained at 15°C. and those of the latter fungus at 20°C. Media buffered at pH 6.4 favored their growth; light had no effect upon yields; and harvests increased markedly in response to shaking. Both fungi required an exogenous supply of thiamin with maximum yields obtained upon incorporating 10μg./l. of the vitamin into a thiamin‐deficient medium. Inorganic nitrogen salts and several organic nitrogen compounds were readily metabolized by these water molds. The use of xylose, glucose, or mannose as the sole source of carbon gave optimal yields of both organisms and neither utilized a variety of sugar acids and alcohols.
STRUCTURE AND DEVELOPMENT OF THE SHOOT IN DOLICOTHELE
Authors: Boke Norman H.
Published: January 2018

Boke, Norman H. (U. Oklahoma, Norman.) Structure and development of the shoot in Dolicothele. Amer. Jour. Bot. 48(4): 316–321. Illus. 1961.—A study of 2 species of Dolicothele reveals that although they have dimorphic areoles and a pattern of spine development similar to those of certain mammillarias, they share a significant number of ectomorphic and endomorphic characters with coryphanthas of the “vivipara group.” These include a tendency toward a cespitose habit; relatively large flowers; green fruits; pitted seeds; medullary vascular systems; forking of the main tubercle traces in the bases of the tubercles; lack of mucilage cells; thin‐walled epidermis and hypodermis, both devoid of crystals; and large, druse‐like crystalline aggregates in older parts of the pith and cortex. The evidence suggests that Coryphantha vivipara and closely allied species are the nearest extant relatives of Dolicothele. It would, therefore, seem inconsistent to return Dolicothele to Mammillaria unless an author's viewpoint were so conservative that he was willing also to return most, if not all, coryphanthas and escobarias to that genus.
STUDIES IN THE QUERCUS UNDULATA COMPLEX. II. THE CONTRIBUTION OF QUERCUS TURBINELLA
Authors: Tucker John M. , Cottam Walter P. , Drobnick Rudy
Published: January 2018

Tucker, J. M. (U. California, Davis), W. P. Cottam, and R. Drobnick. Studies in the Quercus undulata complex. II. The contribution of Quercus turbinella. Amer. Jour. Bot. 48(4): 329–339. Illus. 1961.—Quercus undulata has been interpreted as a hybrid complex involving Q. gambelii and several other species, including Q. turbinella (Tucker, 1961). In the present paper, the total distribution of the hybrids between Q. gambelii and Q. turbinella is given. Lacking direct genetic evidence, proof of hybridity is sought in a demonstration of the morphological intermediacy of these putative hybrids. Population samples of both parental species, other samples containing hybrids, and numerous individual hybrids, are analyzed on the basis of 6 differences between the parental species. The data obtained, presented in the form of pictorialized scatter diagrams, clearly show the general intermediacy of the hybrids. Of the various binomials that have been applied to forms in the Q. undulata complex, Quercus pauciloba Rydb. applies to this hybrid. The appropriate change in status (Quercus × pauciloba Rydb.) is made.
GROWTH INDUCTION IN CULTURES OF HAPLOPAPPUS GRACILIS. II. THE BEHAVIOR OF THE NUCLEUS
Authors: Mitra J. , Steward F. C.
Published: January 2018

Mitra, J., and F. C. Steward. (Cornell U., Ithaca, New York.) Growth induction in cultures of Haplopappus gracilis. II. The behavior of the nucleus. Amer. Jour. Bot. 48(5): 358–368. Illus. 1961.—Cells of Haplopappus, which have been stimulated to grow under the influence of coconut milk and such synergists as naphthalene or 2,4‐dichlorophenoxy acetic acid, can be cultivated as free cells, as small cell clusters, or as peripheral cells on a cultured colony or mass. Such cells display forms and cell lineages, the general pattern of which is reminiscent of those that may occur in early embryogeny. To this extent, Haplopappus resembles what has previously been observed in the growth of free cells of carrot. The form of the normal chromosome of Haplopappus (2n = 4) is described with respect to root tip cells. The range of effects which may be observed in the nuclei of the cultured cell is also described. Such variations as the following were encountered: (1) multinucleate giant cells which may divide by internal segmentation; (2) polyploidy, giving rise to highly polyploid nuclei up to, and even in excess of, 64 chromosomes; (3) somatic pairing; (4) haploidy; (5) pseudochiasmata, with the evident implication of somatic “crossing‐over”; (6) chromosome breaks, reunions and bridges, such as are commonly associated with effects of radiation and with chemical mutagens. Attention is drawn to the usefulness of this material for the further experimental investigation of the biochemical basis for the cytological events which are here described, and, if the variant cells may be cloned, of the relationship between the aberrant nuclear cytology and the ability of the cells or colonies to differentiate or to undergo morphogenesis.
KINETIN MODIFICATION OF SPORELING ONTOGENY IN MARSILEA VESTITA
Authors: Laetsch W. M. , Briggs Winslow R.
Published: January 2018

Laetsch, W. M., and Winslow R. Briggs. (Stanford U., Stanford, Calif.) Kinetin modification of sporeling ontogeny in Marsilea vestita. Amer. Jour. Bot. 48(5): 369–377. Illus. 1961.—Sporelings of the fern, Marsilea vestita Hook. and Grev., were cultured aseptically with a wide concentration range of kinetin. The elongation of the primary and all succeeding roots was significantly inhibited by concentrations as low as 0.3 γ/l., and was almost completely inhibited at concentrations above 30 γ/l. Root inhibition by kinetin was a result of decreased cell division and was not influenced by the amount of available carbon in the medium. The primary leaves also were inhibited by kinetin, but only by higher concentrations. The relative numbers of organs present were altered by intermediate concentrations, with a rise in the number of roots per plant, and a corresponding decrease in the number of leaves. Sporelings maintained in these kinetin concentrations for long periods developed abnormal leaves and roots. The shoot apex lost its organization in higher concentrations and proliferated into callus. The histology of the callus is discussed. The kinetin effects were independent of light conditions. Various other growth‐active compounds were studied in combinations with each other and with kinetin for their effects upon sporelings. Interactions between these compounds were not apparent, and they neither substituted for nor modified the effects of kinetin. The use of kinetin as a tool in morphogenetic study is discussed.
THE LIFE CYCLE AND DEVELOPMENT OF DICTYOMORPHA GEN. NOV. (FORMERLY PRINGSHEIMIELLA), A GENUS OF THE AQUATIC FUNGI
Authors: Mullins J. Thomas
Published: January 2018

Mullins, J. Thomas. (U. Florida, Gainesville.) The life cycle and development of Dictyomorpha gen. nov. (formerly Pringsheimiella), a genus of the aquatic fungi. Amer. Jour. Bot. 48(5): 377–387. Illus. 1961.—The chytrid, Pringsheimiella, originally described by Couch (1939), is renamed Dictyomorpha, because of the previous use of the name Pringsheimiella for an alga. The development and life cycle of the fungus are described. It has been found that the resting spores are initiated by the fusion of isoplanogametes. Couch's observations on heterothallism are confirmed. The validity and relationships of Dictyomorpha are discussed.
THE GROWTH OF A MIDWESTERN STRAIN OF SORGHUM HALEPENSE UNDER CONTROLLED CONDITIONS
Authors: Ingle M. , Rogers B. J.
Published: January 2018

Ingle, M., and B. J. Rogers. (Purdue U., Lafayette, Indiana.) The growth of a midwestern strain of Sorghum halepense under controlled conditions. Amer. Jour. Bot. 48(5): 392–396. Illus. 1961.—This grass, adapted to midwestern growing conditions, increased growth up to 32°C. under long‐day conditions (16 hr.). In a 12‐hr. photoperiod, growth increased up to 27°C; at 32°C. growth was reduced. Flowering usually occurred under photoperiods of 12 hr. or less, but this requirement was not absolute. Rhizome bud sprouting was found to be proportional to temperature. Regardless of the environmental conditions and variations tested, all buds on the rhizomes developed into aerial shoots and never into rhizomes.
DISTRIBUTION AND CELLULAR LOCALIZATION OF ASCORBIC ACID OXIDASE IN THE MAIZE ROOT TIP
Authors: Mertz Dan
Published: January 2018

Mertz, Dan. (U. Missouri, Columbia.) Distribution and cellular localization of ascorbic acid oxidase in the maize root tip. Amer. Jour. Bot. 48(5): 405–413. Illus. 1961.—Ascorbic acid oxidase has been identified by its various properties in homogenates of the maize root tip. Following centrifugal fractionation of the gross homogenate, approximately 30% of the total oxidase activity was found in the soluble fraction, while roughly 70% was bound to the cell wall debris. Quantitative measurements of serial segments revealed that the bound oxidase per cell increases with cell elongation. The very striking parallelism of the bound oxidase activity with that of cell elongation suggests that ascorbic acid oxidase may in some way participate in growth of the cell wall, and have very little to do with cellular respiration.
CULTURE OF STEMONITIS FUSCA ON GLASS
Authors: McManus Mary Annunciata
Published: January 2018

McManus, Sister Mary Annunciata, R.S.M. (Mt. Mercy Coll., Cedar Rapids, Iowa.) Culture of Stemonitis fusca on glass. Amer. Jour. Bot. 48(7): 582–588. Illus. 1961.—The plasmodium of Stemonitis fusca differs in morphology from the type which has been considered characteristic of all Myxomycetes. It lacks the dense granules which are numerous in the physaraceous plasmodium and is, therefore, delicate and transparent, becoming macroscopically visible only when it is about to fruit. It never forms the thick, fleshly fan which is characteristic of the physaraceous type. A simplified method of culture on glass has been developed, which permits excellent visualization of the stages of the life cycle under high magnification and by phase‐contrast illumination.
CYTOGENETIC STUDIES IN THE DRYOPTERIS SPINULOSA COMPLEX. II.
Authors: Walker S.
Published: January 2018

Walker, S. (Liverpool U., England.) Cytogenetic studies in the Dryopteris spinulosa complex. II. Amer. Jour. Bot. 48(7): 607–614. Illus. 1961.—A comparison of the D. spinulosa complex, as represented in North America, is made with that in Europe. Although in North America, other Dryopteris species are known to hybridize with members of the complex, the report has been limited to species which compare directly with those in Europe. Three tetraploid species and 2 diploids, the latter representing at least 1 ancestral genome in the complex, are discussed together with the interspecific hybrids. Synthetic hybrids have been produced, involving taxa from both sides of the Atlantic. Evidence from these hybrids suggests that D. intermedia, of North America, and D. maderensis, of Madeira, are conspecific.
ONTOGENY OF THE INFLORESCENCE IN CHENOPODIUM ALBUM
Authors: Gifford Ernest M. , Tepper Herbert B.
Published: January 2018

Gifford, Ernest M., Jr., and Herbert B. Tepper. (U. California, Davis.) Ontogeny of the inflorescence in Chenopodium album. Amer. Jour. Bot. 48(8): 657–667. Illus. 1961.—Chenopodium album, a short‐day plant, was induced to flower by subjecting it to successive cycles of 7 hr light and 17 hr darkness. After 4 inductive days, the first macroscopic change is evident in the appearance of precocious axillary bud primordia. After 5–6 days, a primordial inflorescence is visible, and after 7–8 days a terminal flower appears on the main inflorescence axis. The vegetative apex has a biseriate tunica, the cells of which are larger than those of the corpus. The cells of the tunica stain lighter, possess larger nucleoli, and are more vacuolate than cells of the subjacent corpus. After photoinduction, the tunica‐corpus organization is maintained, and after 4 short‐days, the shoot apex possesses a mantle of 3–4 layers of cells because there are few periclinal divisions in the cells of the outer corpus. The cells of the mantle stain uniformly and are more chromatic than those of the underlying tissue. Mitotic activity was recorded in the upper 40‐μ segment of the apex. In the vegetative apex, mitotic activity is greater in the lower portion of the segment. Following photoinduction, mitoses increase throughout the apex until a maximum is reached on the 4th day. Also, the plastochronic interval decreases after photoinduction. Nucleoli of cells of the corpus enlarge following induction until all nucleoli of the apex are nearly equal. Included in the paper are discussions of the general morphological differences between vegetative and flowering shoots.
HETEROTHALLISM AND HOMOTHALLISM IN TWO MYXOMYCETES
Authors: Collins O'Neil Ray
Published: January 2018

Collins, O'Neil Ray. (Queens Coll., New York City.) Heterothallism and homothallism in two Myxomycetes. Amer. Jour. Bot. 48(8): 674–683. Illus. 1961.—Single‐spore studies of 2 Myxomycetes, Didymium iridis and Fuligo cinerea, revealed that the former is heterothallic and the latter is homothallic. In D. iridis, 256 single‐spore isolations were made from sporangia which developed in mass‐spore cultures. Of these, 101 germinated and 22 yielded plasmodia that later fructified in most cases. The remaining 79 single‐spore cultures produced clones of myxamoebae and swarm cells only. When 18 of the 79 clones were mated in all possible combinations, plasmodia developed in a pattern which showed that the clones were either (+) or (–) with regard to mating type. Fructifications were readily obtained from these plasmodia. Fifty‐three single spores of the F1 generation were isolated. Of the 44 that germinated, 9 yielded plasmodia in monospore cultures, and 35 produced clones of myxamoebae and swarm cells only. Twenty‐five of the F1 clones were back‐crossed with their parents. Results of the back crosses show that each F1 clone is capable of yielding plasmodia with either the (+) or the (–) parent, never with both. When 14 of the F1 clones were mated among themselves, a (+) and (–) mating type system was again revealed. Most of the 22 original single‐spore cultures which produced plasmodia, later formed sporangia. From these sporangia, 88 spores were isolated. Seventy‐two of these germinated and yielded large populations of swarm cells and myxamoebae, but none produced plasmodia. Twenty of the 72 clones were then mated among themselves. Some matings resulted in plasmodial formation, but the pattern was difficult to interpret. However, when these 20 clones were mated with known (+) and (–) clones, the results appear to be in keeping with a (+) and (–) mating type system. In F. cinerea, 219 single spores were isolated from aethalia derived from mass‐spore cultures. Of these, 144 germinated and the same number yielded plasmodia. Fructifications were easily obtained from such plasmodia. Thirty‐five second‐generation single spores were isolated, of which 15 germinated and 15 yielded plasmodia. These results indicate that F. cinerea is homothallic.
MORPHOLOGY AND HISTOLOGY OF TUMOR TYPES INDUCED BY X, GAMMA, AND BETA IRRADIATION OF A TOBACCO HYBRID
Authors: Hagen George L. , Gunckel James E. , Sparrow Arnold H.
Published: January 2018

Hagen, George L. (The Institute for Cancer Research, Philadelphia, Pa.), James E. Gunckel, and Arnold H. Sparrow. Morphology and histology of tumor types induced by X, gamma and beta irradiation of a tobacco hybrid. Amer. Jour. Bot. 48(8): 691–699. Illus. 1961.—Radiation‐induced tumors of an interspecific hybrid, Nicotiana glauca × N. langsdorffii, were of 6 morphological types: white‐smooth; green‐smooth; green‐tomentose; purple‐pigmented; green‐leafy and stalked, although all intergrades could be found in 1 tumor mass. The morphological responses were essentially the same after treatment with acute X rays, chronic gamma or beta rays. Gamma rays were from an external cobalt‐60 source and beta rays from internally deposited P32. The histology of the 6 morphological tumor types was not distinctive in terms of meristem, vascular and surface development, but rather followed an ontogenetic series from non‐organoid to organoid. The results are discussed in terms of abnormal genome and physiological imbalances, and are compared to similar responses from infection with crown gall and wound‐tumor virus.
THIAMINE METABOLISM IN NEUROSPORA CRASSA
Authors: Eberhart Bruce M. , Tatum E. L.
Published: January 2018

Eberhart, Bruce M. (Princeton U., Princeton, New Jersey), and E. L. Tatum. Thiamine metabolism in Neurospora crassa, Amer. Jour. Bot. 48(8): 702–711. Illus. 1961.—Growth adaptation is a regular feature of the vegetative cycle of thi‐1 strains of Neurospora crassa but not of thi‐2 or thi‐3 strains. The adaptive growth of thi‐1 strains is paralleled by the production of cocarboxylase and carboxylase levels which are similar to those of wild‐type strains. The growth responses of thi‐1,2 and thi‐1,3 double mutant strains to thiamine indicates that the thi‐1 gene is concerned with the utilization (pyrophosphorylation) of thiamine.
ANACHOROPTÉRIS INVOLUTA AND ITS ATTACHMENT TO A TUBICAULIS TYPE OF STEM FROM THE PENNSYLVANIAN OF IOWA
Authors: Hall John W.
Published: January 2018

Hall, John W. (U. Minnesota, Minneapolis.) Anachoropteris involuta and its attachment to a Tubicaulis type of stem from the Pennsylvanian of Iowa. Amer. Jour. Bot. 48(8): 731–737. Illus. 1961.—Petioles referable to Anachoropteris involuta are described, attached to a stem which most nearly corresponds to a member of the genus Tubicaulis. These petioles are attached in a 2/5 phyllotaxy. At their points of departure petiole traces are massive and C‐shaped but become involute in regions away from their attachment. Adventitious roots were borne on the stem in partial whorls. It is suggested that Anachoropteris petioles were extremely long and that they bore adventitious stems at intervals. These, in turn, bore adventitious roots, perhaps to serve for uptake of minerals or support in regions removed from the true stem. Such a “petiole unit” may also have functioned as a vegetative propagule. This would account for the apparent rarity of true stems and the abundance of petioles in coal balls.
NATURE OF THE PLANT COMMUNITY. VI. TEXAS GRASSLAND COMMUNITIES UNDER TRANSPLANTED CONDITIONS
Authors: McMillan Calvin
Published: January 2018

McMillan, Calvin. (U. Texas, Austin.) Nature of the plant community. VI. Texas grassland communities under transplanted conditions. Amer. Jour. Bot. 48(9): 778–785. Illus. 1961.—Clones of 7 grass taxa, Bouteloua gracilis (H. B. K.) Lag., B. eriopoda (Torr.) Torr., B. curtipendula (Michx.) Torr., Panicum virgatum L., the Andropogon scoparius Michx. complex, the Andropogon gerardi Vitman‐hallii Hack. complex, and Sorghastrum nutans (L.) Nash, were transplanted from throughout their distribution in Texas and studied in an experimental garden at Austin. Restricted to western Texas and Panhandle areas, Bouteloua gracilis and B. eriopoda contained similar early‐flowering clones throughout their distribution. Less restricted to western sites, B. curtipendula contained later‐flowering types from eastern and central areas. In the 4 remaining, widespread taxa, early‐flowering potential characterized clones from western sites. These 4 widespread taxa contain the latest‐flowering clones from the coast of southern Texas. Clones of Stipa leucotricha Trin. and Rupr. from a broad area in Texas lacked a flowering gradient. Grassland communities of western Texas and the Panhandle, attuned to short growing seasons and low rainfall, were composed of opportunists, the Bouteloua species, and early‐flowering variants within the widespread species. Communities of central Texas in habitats of highly unpredictable moisture pattern and a relatively long growing season contained later‐flowering variants. Coastal communities attuned to a long growing season contained the latest‐flowering variants.
STUDIES OF THE MOTILE CELLS OF CHYTRIDS. III. MAJOR TYPES
Authors: Koch William J.
Published: January 2018

Koch, William J. (U. North Carolina, Chapel Hill.) Studies of the motile cells of chytrids, III. Major types. Amer. Jour. Bot. 48(9): 786–788. Illus. 1961.—Six major types of chytrid motile cells are recognized on the basis of the internal parts present and their appearances and arrangements. Eighteen species are placed in these 6 types.
AN IAA OXIDASE‐INHIBITOR SYSTEM IN BEAN PODS. I. PHYSIOLOGICAL SIGNIFICANCE AND SOURCE OF THE INHIBITOR
Authors: Sacher Joseph A.
Published: January 2018

Sacher, Joseph A. (Los Angeles State Coll., Los Angeles, Calif.) An IAA oxidase‐inhibitor system in bean pods. I. Physiological significance and source of the inhibitor. Amer. Jour. Bot. 48(9): 820–828. Illus. 1961.—In ‘Kentucky Wonder’ pole bean pod segments, a correlation is shown between the resistance and susceptibility to senescence of exocarp and endocarp, respectively, in the absence of exogenous auxin, and the distribution of a natural, heat‐stable, dialyzable inhibitor of IAA oxidase. The tissues are similar in content of IAA oxidase, but the exocarp, which is resistant to senescence, has a high content of inhibitor. The endocarp, which senesces readily, has none. The greater efficacy of naphthalene acetic acid than IAA in delaying senescence of endocarp, in experiments which minimized or eliminated the effect of the destruction of IAA at cut surfaces, suggested this was due to the endogenous destruction of IAA. But the application of inhibitor did not delay senescence of endocarp. The inhibitor content of exocarp increased 2–5 fold with aging. Reaction mixtures containing non‐dialyzed exocarp enzyme solution showed no IAA destruction for 4 1/2 + hr, while with exocarp slices IAA destruction proceeded rapidly after a 10‐min lag. Evidence is presented which indicates that cytoplasmic particulates are the source of the dialyzable inhibitor.
STUDIES ON THE FLORAL HISTOGENESIS AND PHYSIOLOGY OF PERILLA. III. EFFECTS OF INDOLEACETIC ACID ON THE FLOWERING OF APICAL BUDS AND EXPLANTS IN CULTURE
Authors: Raghavan V.
Published: January 2018

Raghavan, V. (Princeton U., Princeton, N. J.) Studies on the floral histogenesis and physiology of Perilla. III. Effects of indoleacetic acid on the flowering of apical buds and explants in culture. Amer. Jour. Bot. 48(10): 870–876. Illus. 1961.—The responses of apical buds and explants of a short‐day plant, Perilla frutescens (L.) Britt. var. 'Tall Late,' when grown in vitro in White's medium supplemented with indoleacetic acid (IAA) and subjected to short‐days (SD) or long‐days (LD), are described. Additions of varying concentrations of IAA to the medium inhibited the flowering of the photoinduced apical buds in 2 ways. There was a progressive delay in the appearance of the first signs at the apex and a gradual transition from the more flower‐like structures in lower concentrations of IAA (0.1 mg/liter) to sterile cones in higher doses. The sterile cones had florets with well‐developed calyx and corolla lobes, but lacked the sporogenous tissues. When subjected to LD, visible signs were observed only in buds grown in 0.1 and 1.0 mg/liter IAA, the pronounced effect of the auxin being in the step‐wise inhibition in the formation of the non‐sporogenous tissues of the differentiating florets. Flowering of the explants with the 1st pair of unfolded leaves was also inhibited by IAA in either SD or LD, but the 1st signs appeared relatively faster than in apical buds. When photoinduced, explants with the 1st and 2nd pairs of unfolded leaves flowered in all concentrations of IAA tried (up to 100 mg/liter) while those kept in LD remained entirely vegetative.
THE GROWTH AND DIFFERENTIATION OF CULTURED BARLEY EMBRYOS
Authors: Norstog Knut
Published: January 2018

Norstog, Knut. (Wittenberg U., Springfield, Ohio.) The growth and differentiation of cultured barley embryos. Amer. Jour. Bot. 48(10): 876–884. Illus. 1961.—Cultures of excised embryos of barley, Hordeum vulgare L., were made on a number of different media. Growth on White's medium was promoted by adding coconut milk. In the absence of coconut milk, amino acids did not promote growth and differentiation. Embryos as small as 60 μ were successfully grown in vitro. Smaller embryos had the capacity to initiate root and shoot primordia but did not possess the ability to form such embryonic organs as the scutellum and epiblast. Proembryos developed shoots and roots only after a period of irregular growth in which unorganized masses of cells were formed. Multiple centers of shoot initiation were observed in such embryos. The results of the study suggest that, in barley at least, embryonic form may result from an interaction between the embryo and nutritional, spatial and other factors within the ovule.
STUDIES ON POLLEN‐TUBE CHEMOTROPISM
Authors: Rosen Walter G.
Published: January 2018

Rosen, Walter G. (Marquette U., Milwaukee, Wis.) Studies on pollen‐tube chemotropism. Amer. Jour. Bot. 48(10): 889–895. Illus. 1961.—Pollen tubes of several species and hybrids of Lilium are attracted to certain pistil parts of Lilium in vitro. Positive chemotropism is observed with a variety of pistil‐pollen combinations and is independent of the compatibility of these combinations in vivo. The chemotropic factor can be extracted by steeping the pistil parts in water. Chemotropic activity is retained following freeze‐drying of pistil parts or extracts. The active material from L. longiflorum is heat‐labile, dialyzable and not precipitated by acetone. Under certain conditions it causes distention of the pollen tube wall. Chemotropic activity of pistil parts is not simulated by a variety of known compounds or by extracts from various sources other than pistils. A possible mechanism of action of the chemotropic factor is discussed.
STUDIES IN THE GENUS NECTRIA. II. MORPHOLOGY OF N. GLIOCLADIOIDES
Authors: Hanlin Richard T.
Published: January 2018

Hanlin, Richard T. (Georgia Experiment Station, Experiment.) Studies in the genus Nectria. II. Morphology of N. gliocladioides. Amer. Jour. Bot. 48(10): 900–908. Illus. 1961.—Swollen tips of vegetative hyphae develop into multicellular archicarps from which multinucleate ascogonia form. From basal cells of each archicarp arise hyphae which grow up into a prosenchymatous, true perithecial wall; around this wall is formed a thin pseudoparenchymatous stroma of compacted hyphae. The ascogonia give rise to ascogenous cells from which croziers and asci form directly. At the same time, an apical meristem forms cells that grow downward into the centrum. These are pseudoparaphyses. Asci grow up among the pseudoparaphyses, which deliquesce as the ascocarp matures. The ascus tip contains a thick ring with a pore and lateral thickening of the ascus wall. Ascospores are forcibly ejected. The chromosome number is 4. This species conforms to the Nectria Developmental Type of Luttrell.
THE FLORAL ANATOMY OF DIPTERONIA
Authors: Hall Benedict A.
Published: January 2018

Hall, Benedict A. (State U. of New York, Cortland.) The floral anatcmy of Dipteronia. Amer. Jour. Bot. 48(10): 918–924. Illus. 1961.—The floral morphology of Dipteronia sinensis closely resembles that of such species of Acer as A. pseudosieboldianum. Both these species share the following characters: (1) complete flowers; (2) functional unisexuality of staminate flowers, resulting from abortion of the pistil; (3) andromonoecious condition, the same tree bearing both perfect and functionally staminate flowers; (4) nectariferous disc, extrastaminal in position. The vascular anatomy of the 2 species, described in detail in this paper, differs only in minor ways, having similar traces supplying, respectively, perianth, androecium and gynoecium. The greatest difference between the 2 genera lies in the form of the mature fruit, which in Dipteronia has the wings of the samaras completely surrounding the seeds; yet in both genera the vascular skeleton of the fruit is essentially the same. There is a similar cohesion of the vascular traces of sepals and petals in both these species. Differences between these and certain other species of Acer such as A. negundo and A. carpinifolium, herein described, greatly exceed those between A. pseudosieboldianum and Dipteronia. The flowers of A. negundo, for example, have undergone extreme reduction from the presumed ancestral type, having no petals or disc and lacking either stamens or carpels. These facts support the inclusion of Dipteronia in the Aceraceae, but make questionable its status as a genus separate from Acer.
FINE STRUCTURE OF MYCOTA. 7. OBSERVATIONS ON SEPTA OF ASCOMYCETES AND BASIDIOMYCETES
Authors: Moore Royall T. , McAlear James H.
Published: January 2018

Moore, R. T., and J. H. McAlear. (Cornell U., Ithaca, N. Y.) Fine structure of mycota. 7. Observations on septa of Ascomycetes and Basidiomycetes. Amer. Jour. Bot. 49(1): 86–94. Illus. 1962.—Electron microscopy of 13 carpomycete species (5 Ascomycetes, 5 Basidiomycetes, and 3 Deuteromycetes) presents evidence that suggests there is an Ascomycete‐ and a Basidiomycete‐type septum. The observed Ascomycete septa taper slightly or not at all toward a simple, clear‐channel, central pore, while the observed Basidiomycete septa flare sharply and broadly at the center to produce what is termed a dolipore septum. On each side of this septum is a double membrane structure that is crescent‐shaped in section. This is given the name parenthesome. These dolipore‐parenthesome septa were found to be characteristic of basidiocarpic, dikaryotic, hyphae. Interpretative drawings of both types of septa are presented. From these and the micrographs, it is not difficult to see how materials, including nuclei, could pass through the Ascomycete‐type septum, but it would appear that the modifications of the Basidiomycete‐type septum while maintaining cytoplasmic continuity would prohibit nuclear migration in dikaryotic hyphae. It is postulated that as the plant and animal phylogenetic lines have developed actual diploidism, the terminal group of the fungi may have achieved functional diploidism. Of the 3 species of Deuteromycetes examined, 2, Aspergillus variecolor and Stilbum zacalloxanthum, have typical Ascomycete‐type septa; the third, QM 7739, has Basidiomycete‐type septa. This fungus is a species of Sclerotium, but the present confusion and lack of definitive information regarding the taxonomy, genetics, and perfect stage of this genus prohibit the enlarging at present on the possible significance of this observation.
NOCTURNAL THERMAL EXCHANGE OF CITRUS LEAVES
Authors: Turrell F. M. , Austin S. W. , Perry R. L.
Published: January 2018

Turrell, F. M., S. W. Austin, and R. L. Perry. (U. California, Riverside & Los Angeles.) Nocturnal thermal exchange of citrus leaves. Amer. Jour. Bot. 49(2) : 97–109. Illus. 1962.—Cooling rates of leaves were measured with fine thermocouples inserted within the leaf laminae. From these rates, total thermal conductances were calculated for leaves of intact greenhouse‐grown lemon cuttings, in the dark, in still air and moving air, and in open laboratory rooms of warm to freezing temperatures. Thermal conductances were also calculated for leaves of 4 commercial varieties of citrus picked from mature trees in the grove and measured in low light, in still air, in a microcosm at warm, constant temperatures. The total conductances were fractionated, first, by determining transpiration rates of detached leaves from both sources, in darkness and in still or moving air, through similar temperature ranges and humidities. From transpiration rates, transpiration conductances were calculated. Second fractions (radiation conductances) were calculated for lemon leaves from far‐infrared reflectances; and the third fractions (free‐convection conductances) were calculated by subtraction of the sum of the radiation and transpiration conductances from the total. A free‐convection‐conductance coefficient was calculated for lemon, and then applied to 3 other varieties of citrus for which infrared reflectances were unavailable, to obtain their free‐convection conductances. These together with experimentally determined transpiration and total conductances permitted calculation of their radiation fractions. The conductances have been tested for 6 different measured microclimates in which the calculated leaf temperatures averaged ± 0.6 C of the measured temperatures, an error compatible with the precision of field temperature measurements. Total thermal conductances of lemon leaves were higher in both warm, still and warm moving air than in cold, whereas the radiation and free‐convection fractions were about equal in still air. The transpiration fractions were very small in warm, still or warm moving air but negligible in cold. In cold still and cold moving air, all the conductances were larger for orange fruit than for lemon leaves. Leaves of plants native to tropical rain forests were more efficient in heat transfer than were leaves from the temperate zone.
RECIPROCAL TRANSFER OF MATERIALS BETWEEN ALGAL CELLS AND MYXOMYCETE PLASMODIA IN INTIMATE ASSOCIATION
Authors: Zabka George G. , Lazo Waldo R.
Published: January 2018

Zabka, George G. (U. Iowa, Iowa City), and Waldo R. Lazo. Reciprocal transfer of materials between algal cells and myxomycete plasmodia in intimate association. Amer. Jour. Bot. 49 (2) : 146–148. Illus. 1962.—Pure cultures of Fuligo cinerea, a myxomycete, and Chlorella xanthella, a green alga, were separately permitted to accumulate sodium radiophosphate from an agar medium and come into full association with non‐radioactive cultures of the other organism. Manipulation of such mixed cultures indicates that a Plasmodium of Fuligo cinerea and vegetative cells of Chlorella xanthella are both able to absorb radiophosphorus from a nutrient medium and transfer it to each other. It is suggested that these phenomena support the possibility of a symbiotic relationship between the alga and myxomycete in association.
THE HORMONAL INTEGRATION OF SEXUAL REPRODUCTION IN OEDOGONIUM
Authors: Rawitscher‐Kunkel Erika , Machlis Leonard
Published: January 2018

Rawitscher‐Kunkel, Erika, and L. Machlis. (U. California, Berkeley.) The hormonal integration of sexual reproduction in Oedogonium. Amer. Jour. Bot. 49 (2) : 177–183. Illus. 1962.—Sexual reproduction in a heterothallic, nannandrous species of Oedogonium was investigated cytologically and physiologically. Several new observations are reported. Oogonial mother cells release a substance which attracts androspores to them. The androspores, when attached to the oogonial mother cells, grow in well‐defined directions apparently in response to a hormone originating in the oogonial mother cells. An oogonial mother cell divides into an oogonium and a suffultory cell only after the attached androspores complete their development into dwarf males, each bearing an antheridium. Presumably the developing dwarf males provide a chemical stimulus for the division of the oogonial mother cell. During development, the oogonia become enveloped in a massive gel which also encases the antheridia cut off at the apical ends of the dwarf male plants. The gel appears to function as a sperm trap, preventing the dissemination of the sperm into the surrounding liquid. The sperm are attracted to the protoplasmic papilla which briefly protrudes through the oogonial pore indicating the operation of a second chemotactic agent.
CULTURE AND NUTRITION OF AMOEBIDIUM PARASITICUM
Authors: Whisler Howard C.
Published: January 2018

Whisler, Howard C. (McGill U., Montreal, Canada.) Culture and nutrition of Amoebidium parasiticum. Amer. Jour. Bot. 49(3): 193–199. Illus. 1962.—The little known Trichomycete, Amoebidium parasiticum, has been isolated into pure culture Maximum growth was obtained on a thiamine‐enriched Tryptone‐glucose medium. Growth also occurred on a defined medium consisting of thiamine, glucose, methionine, ammonium and inorganic salts. Methionine could not be replaced by sulfate or l‐cystine. Both mannose and fructose could satisfy the carbon requirement. At present, reproduction in pure culture is always by sporangiospores, but the amoeboid phase can be induced by the addition of crushed host material.