bluuebunny/crossref_metadata_2025 huggingface dataset:
GROWTH, DEVELOPMENT AND GEMMA FORMATION IN THE LIVERWORT SCAPANIA NEMOROSA AS INFLUENCED BY L‐ARGININE, L‐HISTIDINE AND L‐GLUTAMIC ACID
Authors: Basile D. V.
Published: January 2018

New procedures of aseptic bryophyte culture which permitted the alteration of the culture medium during the life cycle were used to investigate development and gemma differentiation in Scapania nemorosa from the aspect of organic nutrition. Cultures started from gemmae (asexual reproductive structures) were treated with l‐arginine, l‐histidine and l‐glutamic acid upon reaching each of 3 developmental stages: Cell Mass stage, Juvenile stage, and Early Adult stage. Ten weeks after each treatment, quantitative determinations of growth and gemma formation, as well as a qualitative appraisal of the effect of treatment on development, were made on representative cultures. In addition, an amino acid analysis was made of young plants which had not produced gemmae, of older plants which had produced gemmae, and of gemmae. The results of the culture experiments indicate that all 3 amino acids are stimulatory to production of gemmae and that the degree to which this is so is contingent on the ontogenetic stage treated. Moreover, the qualitative data, in conjunction with the amino acid analysis, indicate that each compound influences gemma formation in a somewhat different manner.
STUDIES ON THE ONTOGENY OF THE DWARF MISTLETOES, ARCEUTHOBIUM. III. DEVELOPMENT OF THE INFLORESCENCE
Authors: Cohen Leon I.
Published: January 2018

In vascular plants, the apical meristem of the shoot normally represents a continuation of growth in the apical meristem of the embryo itself. This is not the case in Arceuthobium. Here the shoot apex of the embryo is rudimentary and eventually dies after infection of the host occurs. The inflorescence of Arceuthobium is, therefore, an adventitious structure originating in the endophytic system rather than from the shoot apex of the seedling. Inflorescence buds arise in either of 2 ways. In some species (A. douglasii and A. americanum), buds first appear as small meristematic protuberances on the outer surface of cortical strands. In other species (A. campylopodum), the buds arise at the ends of short branches. The former, or diffuse, type gives rise to inflorescences along the entire surface of the host branch; in the latter, or condensed, type inflorescences are formed in clusters. Early ontogeny of the inflorescence apex of both types is described. Studies of subsequent growth of the inflorescence apex show 5 well‐defined plastochronic stages: (1) maximal area stage; (2) minimal area stage; (3) early post‐minimal stage; (4) late post‐minimal stage; and (5) pre‐maximal stage.
BIOLUMINESCENCE AND OTHER CHARACTERISTICS OF COLLYBIA VELUTIPES
Authors: Foerster G. Elizabeth , Behrens Patricia Q. , Airth R. L.
Published: January 2018

The growth in terms of linear extension and dry weight, endogenous respiration, bioluminescence and ATP concentration of Collybia velutipes has been considered. After an initial lag phase of approximately 4 days, linear growth extension with time is obtained. Dry weight measurements, however, indicate that secondary activity in previously formed cells occurs. One such activity is the formation of glycogen. The presence of glycogen, as determined by electron microscopy and several chemical tests, has been established in C. velutipes. Optimal endogenous respiratory activity occurs in tissue less than 48 hr of age, while maximal bioluminescent activity occurs in tissue that is 2–6 days in age. The maximum ATP concentration occurs in tissue approximately 7 days old.
ANALYSIS OF PHYLOGENETIC AFFINITIES IN THE TRITICINAE BY PROTEIN ELECTROPHORESIS
Authors: Johnson B. Lennart , Hall Ove
Published: January 2018

Crude seed‐protein extracts of wheat and wheat relatives were fractionated by electrophoresis on polyacrylamide gels. Homology of fractions in the resulting spectra was used as a criterion of genetic affinity among the species and among their genomes. The spectra of Triticum monococcum (AA), T. dicoccum (AABB) and T. aestivum (AABBDD) confirmed evidence from conventional methods that the A and B genomes are different, that the dicoccum A genome is only partially homologous with the monococcum genome, and that the affinity between T. dicoccum and T. aestivum involves the A and B genomes about equally. They also showed the monococcum genome to have more affinity with the aestivum A or both A and D, than with the dicoccum A genome. Protein homologies permitted discrimination of distant as well as close affinities: the spectra of T. monococcum (AA) and Secale cereale (EE) showed no homologous fractions (r = 0.05), while the spectra of T. dicoccum and T. durum (both AABB) showed 10 homologous and 5 sub‐homologous fractions out of 15 (r = 0.92). Previous evidence that an amphiploid spectrum comprises essentially the sum of the fractions in its parental spectra was verified by the dissimilar spectra of T. aestivum (AABBDD) and S. cereale (EE) which accounted for all of the fractions of their amphiploid hybrid, Triticale (AABBDDEE). The effect of each parent upon the amphiploid spectrum was proportional to the number of genomes it contributes.
ANATOMY OF SEEDLING ROOTS OF PSEUDOTSUGA MENZIESII
Authors: Bogar Gerald D. , Smith Frank H.
Published: January 2018

The seedling root system ofPseudotsuga menziesii(Mirb.) Franco consists of the primary root, active long laterals, long laterals that become mycorrhizal, and short roots that may or may not become mycorrhizal. Numerous adventitious roots arise from the pericycle in young roots and from the vascular cambium and pericycle in older roots following pruning. All actively growing apices have a single plate of initials, a complex zonation of mother cells, and a similar pattern of primary tissue differentiation. Short roots and mycorrhizal short roots have 2 plates of initials, one producing the stele and the other the root cap and cortex, and differentiation occurs close to the apex. Primary and adventitious roots are usually triarch, while long laterals are usually diarch as are all short roots. The latter lack secondary xylem, but mycorrhizal short roots may produce a small amount of secondary phloem.
VARIATIONS WITHIN SINGLE CELL CLONES OF TOBACCO TISSUE CULTURES
Authors: Sievert R. C. , Hildebrandt A. C.
Published: January 2018

Comparative studies were made utilizing two series of secondary clones (single cell clones derived from single cell clones H 196 and H 241) of hybrid tobacco (Nicotiana tabacum ♂ × Nicotiana glutinosa ♀ ) tissue grown in vitro. Secondary clones derived from a single parent varied in color, consistency, the ability to grow, and rate of growth with various carbohydrates and growth‐promoting substances. The growth of the secondary clones generally resembled that of the parent clone from which derived. Many of the 23 secondary clones of H 196 grew satisfactorily on media supplemented with sucrose, dextrose, levulose, or maltose; lactose, galactose, and xylose were unsatisfactory supplements. Similarly, the series of 30 secondary clones isolated from H 241 grew well on some media but poorly on others. Growth generally decreased when α‐napthaleneacetic acid or 2,4‐dichlorophenoxyacetic acid was omitted from the basal coconut milk medium. Growth decreased considerably when coconut milk was omitted from the basal medium. The optimum sugar concentration was 1/2 to 1 per cent.
CHEMOTROPIC ACTIVITY AND THE PATHWAY OF THE POLLEN TUBE IN LILY,
Authors: Welk Mariella , Millington W. F. , Rosen Walter G.
Published: January 2018

A study of the pollen tube pathway in Lilium leucanthum var. centifolium and in L. regale reveals that the entire pathway from stigma to ovule is lined with cytologically unique stigmatoid cells. Assays for chemotropic activity of tissues and exudates along the pathway of pollinated or unpollinated pistils showed that onset of chemotropic activity progressed basipetally (and, when pollinated, in advance of the pollen tubes), commencing at the stigma 3‐5 days before anthesis and appearing in the ovules 1‐2 days after anthesis. Activity persists about 10 days in ovules of pollinated pistils and for 14‐16 days in ovules of non‐pollinated pistils. Attempts to localize the source of the chemotropic factor showed that gynoecial tissues bearing stigmatoid cells are chemo‐tropically active while slices of style or ovary wall lacking stigmatoid cells are inactive. When ovules were sliced transversely and the micropylar and chalazal halves assayed, only the micropylar half showed activity. We suggest that the ovules and the stigmatoid tissue along the pollen tube pathway are the sources of the chemotropic factor responsible for the directional growth of the pollen tube.
THE ULTRASTRUCTURE AND COMPOSITION OF THE EGG AND CENTRAL CELL OF COTTON
Authors: Jensen William A.
Published: January 2018

The ultrastructure and composition of the egg and central cell of Gossypium hirsutum (cotton) was investigated. The egg is a large, highly vacuolate cell partially surrounded by a wall. This wall, which is thickest at the micropylar end of the cell, disappears approximately 2/3 of the length of the cell from the micropylar end. The chalazal 1/3 of the cell is surrounded by a plasma membrane. The egg cell shows many characteristics, both in structure and composition, of an inactive cell. No indication of the destruction or formation of cell organelles was found in the egg during the period covered in this study. The central cell is a large, highly vacuolate cell and contains the two polar nuclei. A description of the fusion of the polar nuclei through membrane fusion is given. The nuclear membranes of the polar nuclei are apparently highly active. Indeed, the entire central cell appears active. Much of this activity may be associated with the enlargement of the central cell and the breakdown of the nucellus. The differences in the metabolic condition between the egg and central cell at the time of double fertilization may influence the subsequent initial rate of development of the zygote and the endosperm.
THE BEHAVIOR OF TISSUE CULTURES FROM ENGLISH AND ALGERIAN IVY IN DIFFERENT GROWTH PHASES
Authors: Stoutemyer V. T. , Britt O. K.
Published: January 2018

In both the English and Algerian ivies, Hedera helix L. and Hedera canariensis Willd., leaf dimorphism of the juvenile and the mature, fruiting growth phases is pronounced, the former being a vine with lobed leaves and the latter a shrubby, upright form with entire leaves. Tissue cultures of English ivy started from stems of the two growth phases on the same plant consistently behaved differently, those from the juvenile stage invariably having the higher proliferation rate and larger cells. These differences were maintained consistently in monthly transfers over a period of two years. No medium was found which would support the growth of tissue subcultures of the adult stage of Algerian ivy, but all growth phases of the English ivy were cultured freely in a modified White's medium with additions of coconut water, naphthaleneacetic acid, enzymatic casein hydrolysate, and inositol. Cultures from individual open‐pollinated seedlings of both species varied greatly in proliferation rate but were usually high.
VARIATION IN CHROMATOGRAPHIC PATTERNS IN THE TRAGOPOGON DUBIUS‐PRATENSIS‐PORRIFOLIUS COMPLEX (COMPOSITAE)
Authors: Brehm Bert G. , Ownbey Marion
Published: January 2018

Natural populations of the diploid species, Tragopogon dubius, T. pratensis and T. porrifolius, the F1 hybrids of these species, and the two amphidiploids, T. mirus and T. miscellus, were obtained from the same localities used for previous morphological and cytological studies of the evolutionary relationships of this complex. Inter‐ and intra‐populational comparisons were made utilizing 2‐dimensional chromatograms of these taxa. Members of the complex shared a group of 18 flavonoid‐type pattern components, no one of which was completely species specific. Therefore, species patterns were expressed for a population rather than an individual with pattern components being expressed as a frequency. Patterns for F1 hybrids and amphidiploids, expressed in the same manner, were relatable to the parental species. Diploid species and F1 hybrid patterns were the most variable in areas of greatest sympatry, indicating considerable genetic interchange between species. The distribution of specific components in certain populations was interpreted as chemical introgression. Evidence was presented for separate origins of T. mirus in two localities. The results confirm previous interpretations of the evolutionary relationships in this complex, and when compared to those obtained for Baptisia, they implicate the different breeding systems as important factors in establishing the kind of variation observed.
SENESCENCE: HORMONAL CONTROL OF RNA AND PROTEIN SYNTHESIS IN EXCISED BEAN POD TISSUE
Authors: Sacher J. A.
Published: January 2018

The kinetics of degradation of RNA, total protein, ribosomal and soluble (R‐S) protein and DNA were followed over 24 hours in excised segments of Kentucky Wonder pole beans (Phaseolus vulgaris). In absence of exogenous auxin, RNA degradation proceeded from about zero time. By 15 hours, after about 20% of the RNA had degraded, the degradation of DNA, total protein and R‐S protein was initiated. Exogenous auxin (25 ppm α‐napthaleneacetic acid) prevented these degradations. The addition of kinetin had little or no effect. Auxin enhanced incorporation of orotic acid into RNA two to several times more than it did amino acids into protein. Actinomycin D repressed RNA synthesis about 75% including a repression of auxin‐induced synthesis. It had no effect on the basal level of protein synthesis but did repress auxin‐induced synthesis. The results indicate that the primary action of auxin in preventing senescence of bean endocarp tissue is at the site of RNA synthesis, and the effect of auxin on DNA and protein is a consequence of the effect of auxin on RNA metabolism.
SHOOT APEX DEVELOPMENT OF WINTER BARLEY AS INFLUENCED BY POTASSIUM GIBBERELLATE
Authors: James N. I. , Lund S.
Published: January 2018

Treatment of nonvernalized winter barley plants at early stages of growth with potassium gibberellate accelerated floral initiation and rapid development of shoot apices until after stages of anther formation. Later developmental stages were not stimulated by continued applications of potassium gibberellate or the addition of other plant growth regulators. In some cases supernumerary spikes formed at the lower rachis nodes of the main spike when potassium gibberellate was applied periodically until spike emergence.
PAPER CHROMATOGRAPHY OF AUXINS AND INHIBITORS IN TWO NICOTIANA SPECIES AND THEIR HYBRID
Authors: Bayer Margeet H.
Published: January 2018

Auxins and auxin inhibitors from tissue extracts of normal Nicotiana plants, Nicotiana glauca, N. langsdorffii and their hybrid (which spontaneously produces tumors) were separated by ascending paper chromatography with n‐butanol‐distilled water. An Avena curvature test was used for demonstrating growth‐promoting and growth‐inhibiting substances. IAA could be found in extracts of the parents and the hybrid (RF 0.75). Hybrid tissue yielded the highest amount (37.1°), N. glauca tissue less (30.8°), and N. langsdorffii tissue the least amount (8.5°) of IAA. A second growth promoter (RF 0.35) could be separated from the tissue extracts of the parents and the hybrid, but it showed only low activity in the Avena test. Three inhibitors were present in extracts from N. langsdorffii and the hybrid at RF 0.25, 0.45, and 0.85, whereas N. glauca showed only two of them (RF 0.25 and 0.85). The inhibitor with an RF of 0.45 seemed to be identical with the acidic, benzene‐insoluble “inhibitor β” of Bennet‐Clark and Kefford (1953). The inhibitor (neutral, benzene‐soluble) at RF 0.85 could be found in some tissue extracts of the parents and the hybrid, but showed only little activity in the curvature tests. From neutral and from acidic plant extracts within a pH range of 4.4 to 5.8 a third inhibitor with an RF of 0.25 could be separated. It seems that the high concentration of natural IAA in the hybrid is regulated by a variety of inhibitors with different specificities in the growth‐regulating process. Nicotiana langsdorffii tissue has much less auxin but the same variety of inhibitors as the hybrid, whereas N. glauca tissue contains less auxin than the hybrid and only two of the three inhibitors found in N. langsdorffii and hybrid extracts.
MORPHOGENESIS IN CELL COLONIES GROWN FROM CONVOLVULUS CELL SUSPENSIONS PLATED ON SYNTHETIC MEDIA
Authors: Earle Elizabeth D. , Torrey John G.
Published: January 2018

Filtered cell suspensions of cultured callus tissue derived from the roots of Convolvulus arvensis L. were plated out on synthetic agar nutrient media in petri plates. Cell colonies which formed from the single cells or small cell groups in the suspension showed a considerable range of developmental patterns depending upon the physical and chemical environment to which they were exposed. Variation of the auxin and kinin concentrations and the nature and concentration of the source of reduced N compounds had the most profound effects on colony development. High auxin favored cell enlargement, high kinin favored the development of compact colonies composed of many small cells. Both auxin and kinin were required for cell colony formation. Cell differentiation responses which were observed but not subject to experimental control included formation of starch‐ and crystal‐storing cells, differentiation of tracheary elements, formation of cellular filaments, and development of chlorophyllous tissue. Organ initiation was studied in cell colonies developed directly from plated cell suspensions and in cell colonies subcultured on various nutrient media. Bud initiation was produced repeatedly on media containing NAA at 10‐8 to 10‐6 m combined with kinetin at 10‐6 m. Root initiation was induced infrequently and unpredictably. Once roots had been formed from cell colonies derived from cell suspensions, the roots could be subcultured and induced to form buds; these in turn grew into whole plants. Subculture of young cell colonies to media containing different combinations of growth substances made possible a study of the effects of auxin and kinin on organization of primordia by the cell colonies. By following marked single cells plated on synthetic media, it was possible to produce single‐cell clones which under proper nutrient conditions were induced to form buds. The value of the combined techniques of cell suspension culture and cell plating for the study of the physical and chemical factors influencing cell differentiation and organized development are pointed out.
A HISTOCHEMICAL STUDY OF CALLUS INITIATION FROM CARROT TAPROOT PHLOEM CULTIVATED IN VITRO
Authors: Fosket D. E. , Roberts Lorin W.
Published: January 2018

Cylinders of carrot taproot secondary phloem were cultured on one of four media: 1) 2% sucrose + 1% agar (SA); 2) Heller's basal medium (NA); 3) NA + 10‐5 g/liter 2,4‐D (H4); and 4) NA + H4 + 15% coconut milk (HW). Samples were taken from the cultured explants at 3‐day intervals. A morphological study of the cultured explants revealed no differences between callus‐initiating explants (cultured on HW medium) and noncallus‐initiating explants (cultured on SA, NA, and H4 media) within the first 3 days of culture. All explants exhibited a typical wound response. Cell division ceased in the NA and SA explants after the sixth day in culture. Extensive cell division occurred in the subsurface layer of dividing cells in the HW explants and resulted in the formation of callus by the ninth day in culture. Histochemical staining revealed that the activity of NAD diaphorase, succinic dehydrogenase, and cytochrome oxidase were closely correlated with the wound response and with callus initiation in the cultured explants. The activity of these enzymes was high in the layer of dividing cells of all explants after 3 days of culture, but with longer periods of culture the activity of these enzymes was closely correlated with the extent of cell division. Acid phosphatase activity was associated with the dividing cell layers of all explants, but comparatively little acid phosphatase activity was observed in the NA, SA, and H4 explants as compared to the HW explants, and acid phosphatase was strongly correlated with callus initiation by the HW explants. Using the nitroso reaction, “catechol tannins” were found in the surface layers of the NA, SA, and H4 explants, while no nitroso‐reaction‐positive substances were detected in the HW explants during the period of callus initiation.
COMPARATIVE MORPHOLOGY OF THE CARPEL IN THE ROSACEAE VI. POMOIDEAE: ERIOBOTRYA, HETEROMELES, PHOTINIA, POURTHIAEA, RAPHIOLEPIS, STRANVAESIA
Authors: Sterling Clarence
Published: January 2018

The pomoid genera, Eriobotrya, Photinia, Pourthiaea, Raphiolepis, Stranvaesia, and Heteromeles, have compound inflorescences and biovulate carpels which become papery at maturity. The carpels of all of these except Heteromeles are fused with one another. There are open sutures in the carpels of Heteromeles, Photinia, Pourthiaea, and Raphiolepis, and in these four genera the extent of fusion of the ovular bundle with the wing bundle is related directly to the state of tegumentary fusion and to the extent of fusion of the carpel with the floral cup. In those species of Eriobotrya and Stranvaesia with closed sutures the integuments tend to be fused, as do the ovular and wing bundles, and the carpels are adnate with the floral cup for a considerable distance; in species with open sutures the integuments tend to be free, the ovular and wing bundles tend to be separate, and the extent of fusion of carpel with floral cup tends to be shorter. In genera with connate carpels the wing bundles of adjoining carpels may also be fused. The greatest extent of fusion occurs in Eriobotrya and Raphiolepis, in which there may also be attenuation and disappearance of the wing bundles above the region of ovular insertion and even reduction and disappearance of the carpellary margin.
DIFFERENTIATION AND CONTINUITY OF THE PHLOEM IN THE LEAF INTERCALARY MERISTEM OF LOLIUM PERENNE
Authors: Forde B. J.
Published: January 2018

Serial transverse sections of the stem tip and leaf bases of immature perennial ryegrass leaves were examined to assess the effect of the intercalary meristem on assimilate movement. The development of procambial strands in very young leaves was followed, and the subsequent differentiation of proto‐ and metaphloem examined in both lamina and sheath. In major bundles the first two or three series of protophloem cells differentiated acropetally into the leaf and they or their crushed remnants could be recognized at all levels. A further three or four series of protophloem cells differentiated basipetally, as did the protophloem of all minor bundles and the metaphloem. The basipetal differentiation of the bulk of the phloem combined with crushing of older cells resulted in acute constriction or even complete local blockage of the functional phloem in the active meristematic region. This constriction of the phloem would tend to divert assimilates into the dividing cells both from the stem below and from the mature upper portion of the leaf. No constriction was found at the base of a mature sheath.
CYTOTAXONOMY OF THE CHARACEAE: KARYOTYPE ANALYSIS OF NITELLA OPACA AND NITELLA FLEXILIS
Authors: Sawa Takashi
Published: January 2018

The haploid chromosome complement of Nitella flexilis (n = 12) is composed of two quite different basic karyotypes. One of these is symmetrical and appears to be identical to the karyotype of N. opaca (n = 6), and the other is quite asymmetrical and seems to be identical to that of an apparently undescribed dioecious Nitella from Kansas (n = 6). This may indicate that the monoecious N. flexilis has arisen through hybridization between two dioecious species. Although heteromorphic sex chromosomes were not observed in either species, it appears that female and male potentialities are confined to separate basic chromosome complements and mechanisms determining the monoecious and dioecious states are in close relation to ploidy.
SOME NUCLEAR CHANGES ACCOMPANYING DEVELOPMENT IN THE ENDOSPERM OF GLEDITSIA AND PODOPHYLLUM
Authors: List A. , Hahn K. V.
Published: January 2018

The development of the endosperm in Gleditsia is marked by the growth of the average nucleus from 141 μ3 on June 12 to 978 μ3 on July 14. At the time of formation of a cellular endosperm the average nuclear volume commences dropping and by July 20 reaches an average of 224 μ3 throughout the endosperm. In Podophyllum at the time of cell formation the average nuclear volume begins to drop from a value of about 2850 μ3 and falls to a value of from 500 μ3 to 770 μ3, the latter estimates depending upon the mode of fixation of the material. The volume decrease in the Podophyllum endosperm nucleus is accompanied by a fall in mean relative DNA content of the average nucleus, as determined by microspectrophotometry with the two wavelength method. The possibility of degeneration of some of the higher “ploid” types is considered, as well as depolyploidization.
PACHYTENE CHROMOSOMES OF THE POTATO (SOLANUM TUBEROSUM, GROUP ANDIGENA)
Authors: Yeh B. P. , Peloquin S. J.
Published: January 2018

The morphology of the pachytene chromosomes of haploids (2n = 24) of Solanum tuberosum Group Andigena (2n = 48) is described. Chromosome identification is based primarily on the characteristics of chromatic regions, presence of distinct chromomere(s) in the achromatic regions, and the occurrence of prominent telochromomeres. Chromosomes V, XI and XII have approximately median centromeres. Chromosome II is associated with the nucleolus, and the variation in satellite size of this chromosome can be used as cytological marker for future studies. Comparisons of pachytene chromosomes from different haploids and their hybrids support the concept that the two genomes in Andigena are quite similar. The striking similarity between the potato and tomato chromosomes suggests interesting studies on the evolutionary relationships of these plants.
SYNTHETIC HYBRIDS OF NEW WORLD AND OLD WORLD AGROPYRONS II. AGROPYRON RIPARIUM X AGROPYRON REPENS
Authors: Dewey Douglas R.
Published: January 2018

Five hybrids were obtained from 12 seeds formed in 26 emasculated florets of A. riparium pollinated by A. repens. The hybrid plants were morphologically intermediate between the parents for vegetative and spike characteristics, although they resembled A. repens more closely than A. riparium. The 28‐chromosome A. riparium parent behaved cytologically as an allotetraploid and formed an average of 13.98 II and 0.04 I in 94 cells at metaphase I. An average of 20.27 II and 0.36 IV were observed at metaphase I in 55 cells of A. repens, which was designated as a segmental autoallohexaploid. The hybrids contained 35 chromosomes and averaged 6.75 I, 12.49 II, 1.05 III, 0.01 IV, and 0.01 V in 162 cells interpreted at metaphase I. Bivalent chromosome pairing in the hybrids was attributed to autosyndetic pairing of 2 A. repens genomes and allosyndetic pairing between 1 A. riparium genome and 1 A. repens genome. Multivalent chromosome associations were attributed to structural hybridity. A. repens and A. riparium apparently share a genome in common, and this genome is the one responsible for rhizomes in both species. A. riparium was given a genome formula of R2R2SS; whereas the A. repens genome formula was written as R1R1X1X1X2X2, and the hybrid genome formula was designated as R1R2X1X2S. The “S” genome of A. riparium was derived from A. spicatum, and the “R” genome is the genome shared by A. repens and A. riparium. The origin and distribution of the so‐called “X” genomes of A. repens remain unknown. The hybrids produced from 3 to 10% stainable pollen; however, no seed was set on the hybrids during 2 years in the field.
DISTRIBUTION OF FUNGI IN EARLY STAGES OF SUCCESSION IN INDIANA DUNE SAND
Authors: Wohlrab Gisela , Tuveson R. W.
Published: January 2018

The most common pattern of succession in the most recently active dunes along the southern shore of Lake Michigan is the formation and stabilization of dunes by marram grass, Ammophila breviligulata, the decline of this population after stabilization and its eventual replacement by little bluestem grass, Andropogon scoparius var. septentrionalis. The previously reported distribution of fungi from the sand at 15 cm below the surface in two adjacent communities which represent these stages has been confirmed and the generality of the distribution established for other similar communities of this region and the Warren Dunes State Park in southwestern Michigan. A characteristic fungal flora was isolated from the sand of the Andropogon communities, and 5 fungal species were found to be part of the flora in every one of the communities investigated. No such characteristic flora could be detected in the Ammophila communities. Monthly samples indicated no seasonal variations in the numbers and composition of the fungal flora. The presence of a characteristic fungal flora in the Andropogon communities and its absence in the Ammophila communities indicates a successional trend from a harsh, unstable environment, low in available mineral and organic matter content, to one more stable and suitable for fungal growth.
ONTOGENY AND STRUCTURE OF CONIFEROUS SIEVE CELLS
Authors: Evert Ray F. , Alfieri Frank J.
Published: January 2018

Studies of the secondary phloem of 6 species of conifers revealed that mature sieve‐cell protoplasts contain internal strands which are derived ontogenetically from slime bodies of immature cells. These strands, each measuring about 0.3 μ in diameter, traverse the cell and run from cell to cell through sieve‐area pores. Coniferous sieve cells have much in common—both ontogenetically and structurally—with dicotyledonous sieve‐tube members.
FINE STRUCTURE OF THE DIATOM AMPHIPLEURA PELLUCIDA. II. CYTOPLASMIC FINE STRUCTURE AND FRUSTULE FORMATION
Authors: Stoermer E. F. , Pankratz H. S. , Bowen C. C.
Published: January 2018

The general arrangement of cytoplasmic organelles in Amphipleura pellucida Kutz. is similar to that in other naviculoid diatoms. The chromatophores are parietal with a single, non‐membrane‐limited, pyrenoid. The pyrenoid is crossed by several double‐disc lamellar bands which are occasionally interrupted by less dense areas containing convoluted tubules. Similar areas also interrupt the three‐disc bands of the chromatophores. The nucleus is irregular in shape. The outer membrane of the porous nuclear envelope outfolds around the chromatophore. A perinuclear dictyosome complex is present. Amorphous dense bodies are formed in elaborations of the dictyosomes. Vesicles, both with and without dense inclusions, are formed by the dictyosomes during cell division and a role is suggested for these vesicles in both cytokinesis and frustule development. The first evidence of frustule formation is the deposition of the siliceous median rib within a membranous sac. This sac expands laterally to form the silica deposition vesicle which appears to serve as a mold for the formation of the valve. After the valve is formed, the membranes and the small amount of cytoplasm external to it are sloughed off.
SEXUALITY IN AN AZYGOSPORIC STRAIN OF MUCOR HIEMALIS. I. BREAKDOWN OF THE AZYGOSPORIC COMPONENT
Authors: Gauger Wendell
Published: January 2018

Single‐vegetative‐sporangiospore isolations were carried out on a number of azygosporic cultures of Mucor hiemalis. The resulting cultures were predominantly azygosporic (+) and normal‐appearing (+) while normal‐appearing (–) and azygosporic (–) types were somewhat more rare. While the breakdown of the azygosporic condition is not entirely predictable, it is more evident in older cultures and cultures which have been sub‐cultured. The azygosporic cultures are thought to be bisexual but not sexually heterokaryotic. Sexual heterokaryosis may occur, if briefly, once the breakdown process has been initiated. The production of azygospores is thought to be an expression of the bisexual nature of the azygosporic mycelium.
STUDIES OF THE CELL WALLS OF SCHIZOPHYLLUM COMMUNE
Authors: Wang Chiu‐Sheng , Miles Philip G.
Published: January 2018

Mechanically isolated cell wall materials of eight strains of Schizophyllum commune were studied by chemical and enzymatic procedures. Isolated wall material of each strain was separated by chemical methods into three fractions: A (cold alkali‐soluble, , amorphous), B (warm alkali‐soluble, amorphous), and C (alkali‐insoluble, retaining appearance of hyphal fragments). Chemical tests indicated the presence of chitin in Fraction C and the absence of cellulose, lignin and pectic substances from all fractions. Analyses of acid hydrolysates indicated the presence of glucose in Fractions A, B and C, of hexosamine in Fraction C and the absence of galactose, mannose, 6‐deoxyhexoses, xylose and other pentoses from all fractions. Unfractionated material, Fraction A and Fraction B were slightly attacked by commercial cellulase whereas Fraction C was heavily attacked. Commercial chitinase by itself did not attack Fraction C or unfractionated material to a significant extent. In the presence of cellulase, it was active upon Fraction C. Qualitative differences in cell wall composition between strains were not detected; however, quantitative differences were observed in the proportion of Fraction A and Fraction C as well as in the amount of the various breakdown products in certain strains. It is visualized that the cell wall of this fungus consists of a core of chitin covered by or intermeshed with glucose‐containing polymers.
MODIFIED REMNANTS OF CENTRIPETAL XYLEM IN THE LEAF TRACE OF CEPHALOTAXUS
Authors: Cudia S. J.
Published: January 2018

A study of the leaf traces at the nodes in various species and varietal forms of Taxus, Torreya, Amentotaxus and Cephalotaxus reveals, only in Cephalotaxus, an unusual type of parenchymatous tissue associated with the xylem of the leaf trace. The cells of this tissue occur in one to three layers, have abundant cytoplasm and conspicuous nuclei. The thin walls of these cells are devoid of pits and show spiral or spiral‐reticulate thickenings. These thickenings, although readily taking the counterstain, reveal the presence of lignin as determined by the phloroglucin test and by fluorescence microscopy. This tissue is always internal—that is, adaxial—to the protoxylem of the trace. From the node it accompanies the trace for a short distance into the leaf base, where it gives way centrally to the typical leaf parenchyma and laterally to the transfusion tissue on the flanks of the bundle. In the basipetal direction it is in contact with the inner face of the annular protoxylem of the stele, eventually disappearing in the typical pith parenchyma. This tissue occasionally reveals instances of well‐lignified tracheid‐like centripetal elements. On the basis of the characteristics of this tissue, it is suggested that its origin lies in former centripetal xylem. The significance of this tissue to the evolution of the stele and the systematic position of Cephalotaxus is discussed.
TAXONOMIC IMPLICATIONS OF A COMPARATIVE ANATOMICAL STUDY OF INULOIDEAE‐COMPOSITAE
Authors: Drury D. G. , Watson L.
Published: January 2018

Thirty‐seven species representing eight of the nine subtribes of the tribe Inuloideae‐Compositae were examined for the presence of crystals in the achene wall, fibers within the phloem, and schizogenous resin canals in the aerial stem. Leaf hair type and the size of the widest xylem element were also recorded for each species. These comparative observations point to the presence of two major groups which are completely obscured by current taxonomic practice. Comparative palynological and cytological data already in the literature are readily interpreted in the light of this suggested grouping.
THE INFLUENCE OF GROWTH SUBSTANCES ON THE INDUCTION OF APOGAMY IN PTERIDIUM GAMETOPHYTES
Authors: Whittier Dean P.
Published: January 2018

Experiments employing sequences of three media demonstrated the effect of growth substances on the induction of apogamy. The most effective sequence was 4% sucrose 1–14 days, 4% sucrose plus growth substance 15–28 days, and 0.1% sucrose 29–56 days. In this sequence concentrations of NAA, IAA, and GA promoted apogamous shoot formation. A higher NAA concentration than optimal for shoot formation stimulated apogamous root formation in all medium sequences. Kinetin was without effect or inhibitory to apogamy. Combination of kinetin/GA or GA/NAA concentrations did not increase the apogamous response. One combination of the kinetin/NAA concentrations had a synergistic effect on the apogamous shoot formation. Additions of GA to the synergistic kinetin/NAA combination had an antagonistic effect on the apogamous response.
PIGMENTATION AND SPORULATION IN SELECTED MYXOMYCETES
Authors: Nair Pankajam , Zabka George G.
Published: January 2018

Chemical, chromatographic and spectrometric methods are used to characterize plasmodial pigments and determine relationships between pigmentation and sporulation in selected Myxomycetes. In Physarum gyrosum (white) a single pigment is identified and characterized as a flavone. Physarum polycephalum (yellow) and Didymium iridis (brown) contain four and six components, respectively, in their plasmodial pigments which test negatively for flavones but show the presence of some type of phenolic compound. No detectable component is identified in the white plasmodium of Didymium squamulosum which proved to be independent of light for fruiting. The absorption spectra of all species that were light sensitive for fruiting showed common peaks in the 300–400‐mμ region, among others. Pigment changes associated with light absorption are reported for some white, yellow and brown plasmodial types. In Physarum gyrosum a yellow pigment forms in light which did not show the characteristic flavones present in the white plasmodial stage. Changes in absorption spectra are reported for Physarum polycephalum, Didymium iridis and Didymium squamulosum as the plasmodial pigments change prior to fruiting. Results show a close relationship between the physiology of plasmodial pigmentation and sporulation in the Myxomycete species studied.
TUMORS OF INTERSPECIFIC NICOTIANA HYBRIDS. I. EFFECT OF TEMPERATURE AND PHOTOPERIOD UPON FLOWERING AND TUMOR FORMATION
Authors: Schaeffer G. W. , Burk L. G. , Tso T. C.
Published: January 2018

To establish the flowering and tumor‐forming response of the hybrid Nicotiana suaveolens Lehm. × Nicotiana langsdorffii Weinm., it was grown with the parental species under two temperatures and night‐length photoperiods. All plants flowered earlier with a 2‐hr night interruption. The floral response of N. suaveolens was more sensitive to temperature than that of N. langsdorffii. The response of the hybrid was similar to N. suaveolens in the warm temperatures (24–27 C) and similar to N. langsdorffii in the cool (15–21 C). Tumors on roots of the hybrids were much more pronounced on plants grown in higher temperatures.
RAINFALL PERIODICITY AS A MAJOR FACTOR IN THE FORMATION OF FLOWERING RACES OF CAMPHORWEED (HETEROTHECA SUBAXILLARIS)
Authors: Burk C. John
Published: January 2018

Plants of camphorweed (Heterotheca subaxillaris sensu latiore) were raised in a uniform garden at Northampton, Mass., from seed taken from 19 sites in different parts of the range of the species. Flowering races were observed. Flowering time at Northampton correlated with periodicities of rainfall at the seed source in most instances. The earliest‐flowering plants were obtained from areas where above‐average amounts of rainfall occur in spring, while the later‐flowering plants came from sites where above‐average rainfall occurs in mid‐ to late summer. Other workers have observed a correlation between the frost‐free season and the formation of flowering races in prairie grasses, Eupatorium rugosum, and other plants. There is little correlation between the frost‐free season and the formation of flowering races in Heterotheca and it is postulated that, within the range of camphorweed, periodicity of rainfall is a more critically limiting factor.
A RHIZOPHYDIUM AND ITS HYPERPARASITE ON POLYSIPHONIA
Authors: Johnson T. W.
Published: January 2018

Rhizophydium distinction Petersen and its hyperparasite are reported from Polysiphonia nigrescens in North Carolina. The planonts of R. discinctum, undescribed previously, are posteriorly uniflagellate. Olpidiopsis paradoxus (Petersen) Johnson is proposed as a new combination for the holocarpic, endobiotic fungus parasitizing the Rhizophydium. Early infection stages are evidenced by the accumulation of oil deposits in the host cytoplasm. Resting spores are unknown.
COMPARATIVE MORPHOLOGY OF THE CARPEL IN THE ROSACEAE IX. SPIRAEOIDEAE: QUILLAJEAE, SORBARIEAE
Authors: Sterling Clarence
Published: January 2018

A comparative study of carpellary structure in the spiraeoid subtribes Qui lajeae and Sorbarieae has shown that morphological inter‐relationships are similar to those of other Rosaceae. When the suture is closed the carpels tend to be coherent and the ovular and wing bundles tend to be fused. These relationships are statistically significant in the Spiraeo deae as a whole. The construction of the gynoecium in Lindleya and in most species of Vauquelinia resembles that of a pomoid. Other features of a pomoid‐spiraeoid affinity have been discussed.
EXPERIMENTAL CONTROL OF DNA SYNTHESIZING AND DIVIDING CELLS IN EXCISED ROOT TIPS OF PISUM
Authors: Hof Jack Van't
Published: January 2018

The number of dividing and DNA‐synthesizing cells in excised pea roots can be regulated by eliminating the carbohydrate normally supplied in the culture medium. When the excised roots were allowed to remain for 24 hr in a medium lacking carbohydrate, the number of mitotic figures and tritiated thymidine (H3‐T) labeled cells was reduced almost to zero. After an additional 24 hr in the incomplete culture medium, 15% of the interphase cells were H3‐T labeled, the percentage of the cells that were dividing never exceeded 1.4, and 30% of these were H3‐T labeled. When the roots remained in the deficient medium for 72 hr, neither cell division nor cells synthesizing DNA were observed. Upon addition of 2% sucrose, cell division and DNA synthesis were resumed in the roots that were maintained for 24 or 72 hr without an exogenous carbohydrate supply. It has been hypothesized that some proliferative systems consist of two cellular subpopulations which selectively stop or remain in either the pre‐DNA synthetic (G1) or post‐DNA synthetic (G2) periods of the mitotic cycle. The addition of sucrose, H3‐T, and 5‐aminouracil to the medium, after the roots had been maintained for 24 hr without a carbohydrate, indicated that most of the proliferative cells in the roots had accumulated in either G1, a quasi‐G1 condition, i.e., DNA synthesis stopped sometime before completion, or G2 periods of interphase; the majority, however, were in G1 or quasi‐G1 conditions. The results suggested that DNA synthesis (S period) and mitosis or the onset of these processes have the highest metabolic requirements in the mitotic cycle and that G1 and G2 were the most probable states for proliferative cells in a meristem with a low metabolic level.
STRUCTURE AND COMPOSITION OF ZOOSPORANGIAL DISCHARGE PAPILLAE IN THE FUNGUS ALLOMYCES
Authors: Skucas Gina Purelis
Published: January 2018

A study was made of the discharge papillae of zoosporangia (ZS), as well as of resistant sporangia and gametangia, of Allomyces (mainly A. × javanicus). It was found that they differ considerably. The discharge papillae of the resistant sporangia apparently arise by a blister‐like modification of the inner wall, whereas those of the ZS and the gametangia consist of a pulley‐shaped, refractile plug securely placed in a hole in the wall. This plug can be successfully removed from the ZS wall by treatment with sulfuric acid. Solubility and histochemical tests were used to identify the material of the ZS plugs and the results indicate that the material is a pectic substance, most likely protopectin. The plugs of the gametangia presumably have the same composition. A preliminary study was also made of the discharge papillae of representatives of other families of the aquatic Phycomycetes. The results indicate that such pulley‐shaped plugs filling a pore in the wall are characteristic only of the ZS and the gametangia of members of the family Blastocladiaceae to which Allomyces belongs.
TRILOBOXYLON ASHLANDICUM GEN. AND SP. N. FROM THE UPPER DEVONIAN OF NEW YORK
Authors: Matten Lawrence C. , Banks Harlan P.
Published: January 2018

A new taxon is described from the Upper Devonian, Oneonta formation in the northern Cats‐kills of New York. Triloboxylon gen. n. is represented by petrifactions showing two orders of branching. The main axis bears branches spirally and the latter bear the ultimate appendages spirally. Ultimate appendages branch dichotomously twice, in one plane. Primary xylem of the main axis and branches is three‐armed with mesarch protoxylem extending in a continuous band within each arm. Primary xylem of the ultimate appendage is terete and dichotomizes twice. Metaxylem elements are characterized by scalariform and circular‐bordered pitting on all walls. The cortex is composed entirely of isodiametrical parenchyma cells. Triloboxylon is compared with other genera with three‐lobed protosteles. Its possible affinity with the Aneurophytales is shown. The morphological nature of the “frond” of the Aneurophytales and the possibility that the group possesses the morphological equivalent of simple leaves are discussed.
THE SYSTEMATICS OF PHACELIA MACULATA AND P. DUBIA VAR. GEORGIANA, BOTH ENDEMIC TO GRANITE OUTCROP COMMUNITIES
Authors: Murdy William H.
Published: January 2018

Phacelia maculata and P. dubia var. georgiana are endemic to granite outcrop communities in the southeastern Piedmont of Alabama, Georgia, and South Carolina. Data are presented in support of the hypothesis that P. maculata is a relict species, whereas P. dubia var. georgiana is an ecotype recently derived from the Appalachian P. dubia. P. maculata is restricted to undisturbed outcrops of the central and upper Piedmont, and its center of distribution coincides with that of other well‐known, relict endemics. It lacks intraspecific variability and has a narrowly circumscribed habitat which has recently undergone contraction. P. dubia var. georgiana is absent from most of the undisturbed outcrops, but it occurs in abundance at outcrop sites of the lower Piedmont of Alabama and Georgia which have been recently disturbed. It is variable and will successfully compete with well‐established outcrop species in a variety of open habitats. Both its habitat and range are expanding with the increase of man's disturbance of the outcrop habitat, especially in the form of pasturing and cultivation. Each taxon is morphologically distinctive throughout its entire range, and population studies reveal no evidence of introgression in regions where they are sympatric. Reproductive isolation is complete and is effected by means of a postfertilization, incompatibility factor.
THE MORPHOLOGY AND CYTOLOGY OF PREUSSIA FUNICULATA
Authors: Kowalski Donald T.
Published: January 2018

The vegetative nuclei of Preussia funiculata (Preuss) Fuckel appear to divide in two ways. One is very similar to mitosis in higher plants except that no typical metaphase is present. The other consists of elongated nuclei splitting longitudinally into two halves. Ascocarp development is similar to that found in the Pleosporales. A stroma originates in an intercalary position on a hypha. It increases in size, and the outer cell layers differentiate to form the wall. The ascogenous system arises from multinucleate ascogonial cells scattered throughout the centrum. These give rise to large, lobate, multinucleate cells which in time form asci by means of croziers. The mature centrum contains a distinct hymenium and paraphysoids. The haploid chromosome number appears to be 12.