bluuebunny/crossref_metadata_2025 huggingface dataset:
A CYTOCHEMICAL STUDY OF EMBRYO DEVELOPMENT IN STELLARIA MEDIA
Authors: Pritchard Hayden N.
Published: January 2018

The caryophyllad type of embryogenesis in Slellaria media was investigated using topological cytochemical methods for the demonstration of nucleic acids, proteins and polysaccharides. The primary suspensor cell initially contained high levels of cytoplasmic RNA, but these declined rapidly after the first few cell divisions. Cytoplasmic protein levels were high throughout the existence of the primary suspensor cell, becoming concentrated into proteinoplasts at the time of cotyledon initiation in the embryo. These plastids were RNA‐ and DNA‐negative, and only slightly positive with methods for polysaccharides and lipids. Cytoplasmic and nucleolar RNA and protein levels were high in the embryo throughout its development. The cotyledons and endosperm also showed high RNA and protein levels. Cytoplasmic DNA was present in the embryonic apical meristematic cells in the form of Feulgen‐positive, deoxyribonuclease‐removable granules. Cytoplasmic histones were present in the embryo and endosperm. Polysaccharides were demonstrable in the cotyledons, cortex, endosperm, and nucellus.
MODIFICATION OF THE VEGETATIVE DEVELOPMENT OF PHASEOLUS VULGARIS WITH N,N‐DIMETHYLAMINOMALEAMIC ACID
Authors: Bukovac Martin J.
Published: January 2018

Bean plants treated with N, N‐dimethylaminomaleamic acid (DMAM) were characterized by a reduction in plant height, dark‐green foliage, short, thick internodes, restricted petiole extension, and, at high concentrations, a slight reduction in leaflet expansion and dry matter accumulation. DMAM specifically affects internodal and petiolar tissues. The inhibitory stimulus of DMAM is readily translocated following application to a single leaf and the subsequent suppression of stem elongation increased with increasing dose. The failure of the rachises of the trifoliate leaves to fully extend resulted in an overlapping of the bases of the lamellae of the individual leaflets. The inhibitory effects of DMAM on stem elongation can be completely reversed with gibberellin A3 (10 or 100 ppm). This might suggest, that DMAM may be interfering with the natural synthesis of gibberellin in the plant.
THE COPRINOID STATE OF RHACOPHYLLUS LILACINUS
Authors: Maniotis James
Published: January 2018

Rhacophyllus lilacinus was obtained in moist chamber from bark collected in Austin, Texas. A perfect state of an undescribed fungus, Coprinus clastophyllus sp. nov., developed in laboratory culture from R. lilacinus. Some morphologic, cultural, cytologic and genetic features of both states are discussed and illustrated.
CHROMOSOME NUMBERS IN COMPOSITAE V. ASTEREAE II.
Authors: Solbrig Otto T. , Anderson Loran C. , Kyhos Donald W. , Raven Peter H. , Rüdenberg Lily
Published: January 2018

Reports of 100 new chromosome counts are made for the tribe Astereae of Compositae, mostly based on determinations of meiotic material, including first counts for 9 genera and 53 species. Counts are now available for 58 of the approximately 100–120 genera and 431 of the approximately 2000 species in the tribe. Comparisons are made between chromosome number and habit and also between chromosome number and geographical distribution. Species and genera with a basic number of x = 9 are the most abundant. Within different phyletic lines x = 9 is also the most abundant number. On the other hand, many species with x = 4 and 5, belonging to a number of small, largely annual genera, are concentrated in southwestern North America. The low chromosome number in these plants is probably correlated with the dry habitat they occupy, and is most likely a specialized condition.
RADIATION AND CONVECTION IN CONIFERS
Authors: Tibbals E. C. , Carr Ellen K. , Gates David M. , Kreith Frank
Published: January 2018

The transfer of energy to and from a conifer branch involves solar radiation, thermal radiation from the ground, atmosphere, and surroundings, thermal emission by the branch, and free convection in still air and forced convection in wind. It is necessary to know the actual surface area of the branch, the effective area for absorbing sunlight, the effective area for absorbing long wave thermal radiation and for emission, and the free and forced convection coefficients. These parameters are determined using silver castings of blue spruce and white fir branches suspended in an evacuated radiation chamber and in a wind tunnel. The actual surface area of a branch is determined by means of an electrolytic technique. Numerical examples are given for energy transfer in a natural environment for conifers and comparison is made to a broad deciduous type of leaf. The role of transpiration in the energy transfer process is discussed.
THE EXTRACTABLE AND DIFFUSIBLE AUXIN‐AUXIN INHIBITOR LEVEL IN NICOTIANA GLAUCA, NICOTIANA LANGSDORFFII AND THEIR AMPHIDIPLOID HYBRID
Authors: Bayer Margret H. , Hagen George L.
Published: January 2018

The auxin‐auxin inhibitor (effective auxin content—EAC)2 level of stems and leaves of normal Nicotiana plants (N. glauca, N. langsdorffii and of their spontaneously tumor‐producing hybrid) was investigated by the use of the diffusion method into agar blocks and by the wet‐ether and wet‐alcohol extraction method. In all series, the EAC was tested by the Avena curvature test. Although the Avena curvature produced from extracts and diffusates in these tobacco plants is low, in general there is a consistently greater curvature in the parents (on an average for N. glauca, 6.7° in the diffusion and 6.2° in the extraction tests; for N. langsdorffii, 2.7° in the diffusion and 4.6° in the extraction tests) than in the hybrid (on an average of 0.7° in the diffusion and 2.6° in the extraction tests). This suggests that the question “Why do tumors form in the hybrid?” cannot be answered simply by suggesting that it is a function of excessive auxin. It is known that IAA must be added in high concentrations to aseptic cultures of N. langsdorffii and N. glauca whereas cultures of hybrid tissues do not require such an exogenous auxin supply for growth. This might indicate differences in the availability of IAA for growth of these tissues.
MORPHOLOGY OF MARSILEA VESTITA. II. MORPHOLOGY OF THE ADULT LAND AND SUBMERGED LEAVES
Authors: Gaudet John J.
Published: January 2018

Two distinct adult leaf forms, i.e., land and submerged leaves, of the aquatic fern Marsilea vestita were collected from nature and were obtained from plants in sterile culture. The venation patterns and anatomy of these 2 adult leaf forms are presented in detail. Pinna development and the morphology of a third leaf form, i.e., floating leaves, are briefly considered. The differences in leaf form are ascribed to differences in the activity of the marginal meristem of the leaf.
SYNTHETIC HYBRIDS OF NEW WORLD AND OLD WORLD AGROPYRONS. I. TETRAPLOID AGROPYRON SPICATUM × DIPLOID AGROPYRON CRISTATUM
Authors: Dewey Douglas R.
Published: January 2018

Four interspecific hybrids of tetraploid A. spicatum × diploid A. cristatum ‘Fairway’ were obtained by controlled pollinations of emasculated and unemasculated spikes of A. spicatum. Most vegetative and spike characteristics of the hybrids were intermediate between those of the parent species. Tetraploid A. spicatum behaved cytologically as an autotetraploid, with mean chromosome associations of 0.09 I, 7.95 II, 0.03 III, and 2.98 IV being observed in 103 cells interpreted. The diploid A. cristatum was cytologically regular and formed 7 bivalents in 160 of 163 cells examined. Meiosis in the triploid hybrids was highly irregular, and these plants were completely sterile. Chromosomes of A. spicatum and A. cristatum differed sufficiently in size so that they could be distinguished in the hybrids. Seven bivalents and 7 univalents were formed in 90.5% of 262 cells interpreted at metaphase I. Mean chromosome associations of 6.87 I, 6.98 II, and 0.05 III were observed in the hybrids. Most chromosome pairing was due to autosyndesis of A. spicatum chromosomes, but A. cristatum chromosomes occasionally paired among themselves and with A. spicatum chromosomes. Tetraploid A. spicatum was considered to be an autotetraploid. On the basis of cytological evidence, A. cristatum, A. spicatum, and their interspecific hybrids were represented by genome formulae of AA, BBBB, and ABB, respectively.
AN ODOROUS BASIDIOBOLUS OFTEN PRODUCING CONIDIA PLURALLY AND FORMING SOME DICLINOUS SEXUAL APPARATUS
Authors: Drechsler Charles
Published: January 2018

A coarse fungus isolated from decaying plant detritus originating in northern Wisconsin and western Maryland is newly described as Basidiobolus magnus. Like B. ranarum, it gives off an odor recalling benzene hexachloride. Its mycelium, especially while young, includes many long segments markedly wider in the middle than at the ends. Its distally phototropic conidiophores sometimes are branched in their procumbent or submerged portions, and each propulsive distention may bear 1–3 globose conidia, which may be shot off forcibly or may fall through collapse of the supporting hypha. The primary globose conidia of B. magnus are generally larger than those of B. ranarum, from which they differ further in sometimes giving rise to plural secondary conidia of either the globose or the elongated adhesive type. The zygospores, like those of B. ranarum, show abundantly undulated sculpture but differ in their generally larger size, their occasional origin through conjugation between cells of separate hyphae, their rather frequent binary development, and their germination by production, often, of 2 globose uninucleated conidia. The elongated conidia, which seem generally no bigger than those of B. ranarum and are often only meagerly tipped with adhesive material, sometimes undergo conversion into sporangia through internal segmentation.
PHOTOSYNTHESIS AND RESPIRATION OF ALPINE LICHENS
Authors: Bliss L. C. , Hadley E. B.
Published: January 2018

Photosynthetic and respiratory rates were studied in Cetraria islandica, C. nivalis, and Cladonia rangiferina in the alpine zone of Mt. Washington, New Hampshire. Measurements were made in the field using an infrared gas analyzer; light, temperature, and thallus water content were varied. In all species, considerable reduction in photosynthesis and respiration occurred with drying, more rapidly in photosynthesis than respiration. Optimal photosynthetic rates in all 3 species occurred at 15–20 C with light levels of 1,600 ft‐c. Light compensation points ranged from 200 to 350 ft‐c. Optimal respiratory rates were attained at 15 C in the 2 species of Cetraria and at 20 C in Cladonia. The data indicate that these wide‐ranging, arctic‐alpine and arctic‐temperate lichens on Mt. Washington are quite well adapted to a moist, foggy environment with cool temperatures and low light levels, conditions which predominate in summer.
THE PYRENOID OF SCENEDESMUS QUADRICAUDA
Authors: BlSALPUTRA T. , WEIER T. E.
Published: January 2018

The development of the pyrenoid of Scenedesmus quadricauda from the time of its initiation and its subsequent activities is described in some detail. Correlation is made between the evidence from light and electron microscopy. The pyrenoid is a dynamic organelle which continues to change its appearance throughout the development of the algal cell due to the following factors: the deposition of starch platelets within the periphery of the expanding matrix; the separation of starch grains into individual pockets by the intrusive growth of the chloroplast lamellae in centripetal fashion; and the transition of the shape of the starch from concavo‐convex platelets to lenticular grains. By these processes starch grains are continuously formed by deposition of carbohydrates within the matrix. The grains accumulate within the chloroplast, maintaining an organic connection with each other by slender starch bridges. Some parental starch grains are passed on to daughter cells during cell division. By taking into account the planes of cleavage during cell division, it is not difficult to see that pyrenoid starch grains could become distributed throughout the daughter chloroplast, regardless of their distance from the pyrenoid.
MORPHOGENESIS IN VERTICILLIUM: A SELF‐PRODUCED, DIFFUSIBLE MORPHOGENETIC FACTOR
Authors: Brandt W. H. , Reese Judith Edwards
Published: January 2018

A microsclerotial isolate of Verticillium albo‐atrum produces a diffusible morphogenetic factor (DMF). At certain levels, DMF stimulates production of microsclerotia and melanin and inhibits hyphal elongation and sporulation. At higher concentrations it can inhibit production of microsclerotia and melanin as well as germination of Verticillium spores. Near‐ultraviolet radiation (mostly 3200–4000 A, emission peak 3650 A), which inhibits production of microsclerotia and melanin, appears to act by suppressing synthesis of DMF. Once formed, DMF withstood 5 days’ exposure to near‐UV. Dark‐reared liquid cultures (shake or still) produced DMF while those reared under near‐UV did not. DMF is active from pH 4 to pH 10, seems to be non‐volatile, is dialyzable and water‐soluble. In preliminary tests, it was insoluble in ether, ethanol and methylene dichloride. Acetone inactivated it. It may be 1 substance or a group of substances. We have developed assays for DMF in agar and liquid media employing the germination of Verticillium spores.
MONOPLOIDS AND DIPLOIDS OF MAIZE: A COMPARISON OF GENOTYPIC EQUIVALENTS
Authors: Chase Sherret S.
Published: January 2018

Comparison was made of 10 monoploid and 10 diploid plants in each of 6 lines (3 inbred lines and 3 monoploid‐derived homozygous diploid lines) of maize to test the hypothesis that the monoploid, having, presumably, half the chromosomal volume per nucleus of the related diploid, would be proportionally scaled down in all dimensions and, having a complete gene complement, would retain the same number of parts as the diploid. In fact the monoploids were found to be slightly smaller than expected, with, in general, fewer parts than their diploid sibs. The difference was of the order of 11% in terms of both number of parts and linear dimensions, with area and volume measures proportionately scaled. It is suggested that the deviation from expectation could have been due to precocious nuclear and cell division in the monoploid consequent to the relation of chromosomal and nuclear volume to cell surface area, or the bias could be attributed to an environmental disadvantage peculiar to the monoploid plants.
PLATYZOMA—A QUEENSLAND FERN WITH INCIPIENT HETEROSPORY
Authors: Tryon Alice F.
Published: January 2018

First record is made of a dioecious condition in the heterosporous, terrestrial fern Platyzoma microphyllum R. Br. from northern Australia. The spores, gametophytes and young sporophyte are described and the role of heterospory and dioecism in these plants is discussed. The genus is newly classified as a subfamily Platyzomatoideae in the Polypodiaceae.
FINE STRUCTURE OF THE DIATOM AMPHIPLEURA PELLUCIDA. I. WALL STRUCTURE
Authors: Stoermer E. F. , Pankratz H. S.
Published: January 2018

A description of the frustular morphology of Amphipleura pellucida, based on electron micrographs of both entire frustules and sectioned material, is presented. The wall of the valve proper is of uniform thickness except for the thickened central nodule and the ribs surrounding the raphe. The regularly arranged punctae are about60mμ in diameter. Their internal opening is covered by a thin, porous plate with pores about 6‐8mμ in diameter. Each intercalary band contains an elongate chamber which opens to the interior of the cell by a series of oval foramina and to the exterior by a slit between the valve mantle and intercalary band. The lower margin of the intercalary band contains a series of elongate foramina. Both types of foramina are covered, on the internal margins, by porous plates similar to those which cover the internal openings of the punctae.
PHYSOSTOMA CALCARATUM SP. NOV., A TENTACLED SEED FROM THE MIDDLE PENNSYLVANIAN OF KANSAS
Authors: Leisman Gilbert A.
Published: January 2018

A new species of Physostoma is described from Kansas coal balls of Middle Pennsylvanian age. The seed is small, ovoid, and radially symmetrical. The integument consists of 6–10 rounded segments, fused in the lower half of the seed but free in the upper. Distinct spurs are formed by the segments near the base of the seed. The integument is essentially non‐sclerified and has a distinct blow‐off epidermis. Each segment is supplied by a single vascular trace. The pollen reception mechanism consists of a short cylindrical salpinx, a bell‐shaped lagenostome, and a shallow plinth. A central column is present within the salpinx. It is suggested that the Upper Carboniferous seed genera Conostoma and Physostoma may have been derived from the Lower Carboniferous genera Salpingostoma‐Euryostoma and Genomosperma‐Hydrasperma, respectively.
IMPLICATIONS OF NUCLEOLAR DIFFERENCES IN THE ROOT EPIDERMIS AMONG SEVERAL GRASS SPECIES
Authors: Lewis Robert F. , Rothwell Norman V.
Published: January 2018

The nucleolar sizes of root epidermal cells were determined in 10 species of the Gramineae. Festucoid and panicoid roots presented significantly larger nucleoli in hair‐producing, as opposed to hairless, cells. The magnitude of the nucleolar size differences between cell types seemed to be species specific and was not related to the type of epidermal cellular pattern. There seemed to be some suggestion that meristematic nucleoli of festucoid species may generally be larger than those of panicoid types. There was also an indication that festucoid grasses might be characterized by a high percent of multinucleolate epidermal cells. In contrast, cells of panicoid roots contained a single nucleolus in most instances. Possible implications of these observations were briefly discussed in terms of development and systematics.
ECOTYPIC DIFFERENTIATION WITHIN FOUR NORTH AMERICAN PRAIRIE GRASSES. I. MORPHOLOGICAL VARIATION WITHIN TRANSPLANTED COMMUNITY FRACTIONS
Authors: McMillan Calvin
Published: January 2018

Ecological variation within transplanted community fractions, containing Andropogon scoparius Michx., A. gerardi Vitman, Panicum virgatum L. and Sorghastrum nutans (L.) Nash, included broad behavioral and morphological differentiation. In Austin, Texas, during 1958–1962, southern community fractions that contained early spring activity, late flowering and late fall dormancy included taller plants than early‐flowering, northern community fractions. The tallest populations in all 4 species originated in Texas. In P. virgatum, size of leaves and panicles showed north‐south trends similar to culm height values. Leaf pubescence and leaf glaucousness in all 4 species showed geographic patterning that was not correlated with north‐south maturity gradients. Greatest pubescence was on clones in community fractions from pine woods in the Southeast. Glaucousness was concentrated in community fractions from central Texas northward to Nebraska.
THE CRYOFLORA OF THE PACIFIC NORTHWEST
Authors: Garric Richard K.
Published: January 2018

Descriptions of 24 species of cryophylous algae and 3 species of microfungi are given. Ten of these algae are new records for the algal flora of continental North America. The organisms grouped in the species Chlamydomonas nivalis were found to be by far the most common member of the red snow flora, being found in every area of the Pacific Northwest from which collections were made. Green snow is described from the Olympic National Park, having as its causative agent either Chlamydomonas yellowstonensis, or other snow algae which had lost the characteristic masking (red‐to‐yellow pigmentation) as a result of the population developing in shade. Other members of the snow's flora included species of the following genera: Scotiella, Chodatella, Raphidonema, Tetraëdron, Mycanthococcus, Stichococcus, Chlorosphaera, Protococcus, Gloeothece and Romeria. The 3 fungi identified are: Selenotila nivalis, Chionaster nivalis and Chionaster bicornis. Kol's silicotrophic‐calcitrophic theory which relates the red and green snow vegetation types to the underlying rock composition is evaluated, and it is concluded that there is no sound reason for this correlation. It is suggested that the degree of illumination is a more important factor in determining the distribution of these pigmented organisms.
HETEROKARYOSIS AND PARASEXUALITY IN THE FUNGUS ASCOCHYTA IMPERFECTA
Authors: Sanderson K. E. , Srb A. M.
Published: January 2018

The object of this investigation was to discover whether heterokaryosis and parasexuality occur in the imperfect fungus Ascochyta imperfecta. Both phenomena have been observed. The wild type of A. imperfecta grows on a minimal medium containing only salts plus a carbon source. Auxotrophic and morphological mutants have been isolated after treatment with ultraviolet light. When 2 different mutant auxotrophs are inoculated together onto minimal medium, colonies are consistently formed. These colonies might be due, a priori, to back‐mutation, diploidy, syntrophism or heterokaryosis. Back‐mutation and diploidy have been eliminated, since no back‐mutant nuclei have been isolated from any heterokaryon, and since the frequency of diploid nuclei is very low. The combination is primarily syntrophic (only 2% heterokaryotic hyphal tips) when the nicotinamide mutant is one component. The combination is primarily heterokaryotic (over 50% heterokaryotic hyphal tips) when both components are auxotrophs for amino acids. From the heterokaryotic hyphal tips, the 2 unaltered nuclear components have been isolated. Heterozygous diploid nuclei (4.2 X 10−‐7 per haploid nucleus) can be isolated from heterokaryons by plating, onto minimal medium, the primarily uninucleate conidia from a heterokaryon of 2 auxotrophs. The resulting colonies are isolated as potential diploids. Three properties of these isolates establish their diploid nature: (1) the isolates are wild type for nutrition and morphology; (2) their conidial length is uniformly greater than that of the haploids (1.21 times); (3) the isolates produce segregants with nonparental combinations of the marker genes. The diploid isolates are much more stable than heterokaryons. The recombinants from the diploids are still diploid, since (1) their conidial length falls in the diploid range, and (2) one of the recombinants has segregated a second‐order recombinant. Many of the expected classes of recombinants have not been detected.
POLLEN MORPHOLOGY AND EVOLUTION IN HEDYOTIS SUBGENUS EDRISIA (RUBIACEAE)
Authors: Lewis Walter H.
Published: January 2018

Primarily on the basis of aperture structure, 31 species of Hedyotis subg. Edrisia (Houstonia) are separable into 5 palynological groups. Group 1 is characterized by a simple os circumscribed by varying nexinous thickenings, groups 2–4 combine this os with a crassimarginate one to form a compound os, while group 5 is known only with the crassimarginate os. The first type is considered primitive, the compound os specialized and more advanced, and the third type reduced and highly advanced. Other characteristics of the pollen, including size and shape, aperture number, thickness of sexine and nexine, and reticulum, are discussed in relation to the apertures, and their probable primitive and advanced expressions are outlined. The data agree with the phyletic trends found in the sporophyte on the basis of results from morphology, chromosome number and size, and distribution, and they support and add to an earlier phylogenetic scheme proposed for the subgenus. The evidence from palynology also supports the treatment of Hedyotis and Houstonia as congeneric.
THE ACRASIEAE IN NATURE. II. FOREST SOIL AS A PRIMARY HABITAT
Authors: Cavender James C. , Raper Kenneth B.
Published: January 2018

Although the Acrasieae are widely distributed in nature, they are most numerous and of the greatest variety in forest soils. Those species isolated from deciduous forest soils of Eastern and Midwestern United States belong to 2 families, the Dictyosteliaceae and Acytosteliaceae. Preference of the Acrasieae for forest soils over those of grassland was demonstrated by sampling a vegetational succession from prairie to forest. Occurrence of these slime molds within the forest soil profile is largely confined to the surface of the humus layer and the fermenting leaf litter. The Acrasieae are more numerous in forest soils in the autumn and spring than at other seasons. The frequency of occurrence of species varies considerably along the forest continuum of southern Wisconsin, indicating a differential response to microenvironments as influenced by the higher vegetation.
THE ACRASIEAE IN NATURE. III. OCCURRENCE AND DISTRIBUTION IN FORESTS OF EASTERN NORTH AMERICA
Authors: Cavender James C. , Raper Kenneth B.
Published: January 2018

The distribution of 9 members of the Acrasieae in the climax associations of the temperate deciduous forest of Eastern North America was determined. No undescribed species were isolated. The presence, density, relative density, and frequency of species were found to fluctuate with the environment as indicated by the dominant trees in the forest canopy. The acrasian population of the lowland hardwood forest (silver maple‐American elm) differs markedly in relative density and frequency of its constituent species from that of any upland forest. High frequencies of Polysphondylium pallidum and Dictyostelium polycephalum characterize this forest type. In the upland forest, D. minutum is the most characteristic species and maintains a high frequency and relative density over most of the forest area; however, it decreases in importance in southern regions. The relatively dry oak‐hickory association was found most favorable for the development of the Acrasieae. Soils of the boreal forest contain only limited numbers of Acrasieae representing few species.
PALEOZOIC LYCOPSID FRUCTIFICATIONS. I. LEPIDOCARPON PETRIFACTIONS
Authors: Balbach Margaret Kain
Published: January 2018

A reinvestigation of the 4 American species of Lepidocarpon described from petrifactions and of Illiniocarpon cadyi, also described from petrifactions, shows that they are all conspecific. When they, in turn, are compared with specimens of the British petrifaction L. lomaxi, no significant differences can be demonstrated. The criteria cited as diagnostic for the American petrifaction species of Lepidocarpon were found to fail as bases of discrimination when 400 specimens of Lepidocarpon found in coal balls of Pennsylvanian age were studied. Measurements and observations made of a sample size of 136 of these 400 specimens reveal a degree of variation compatible with that of a single species. All previously described American and British petrifaction taxa fall within (or not significantly beyond) this range of variability of a single species as determined from this sample. Additional evidence concerning the 3‐dimensional sporophyll structure of this one species of Lepidocarpon and the configurations obtained by certain planes of section through it have served to demonstrate that Illiniocarpon cadyi is in reality a taxon based on sectioned structures of the sporophyll of this Lepidocarpon species. Under the rules of priority, this species of Lepidocarpon and the following are assigned to Lepidocarpon lomaxi: Illiniocarpon cadyi, Lepidocarpon ioense, L. magnificum (megasporangiate form), L. crenatum and L. palmerensis. On the basis of the morphological evidence, the British petrifaction described as Lepidocarpon wildianum is also equated with L. lomaxi.
CHROMOSOME NUMBERS IN POPULATIONS OF CLAYTONIA VIRGINICA FROM THE NEW YORK METROPOLITAN AREA
Authors: Rothwell Norman V. , Kump Joseph G.
Published: January 2018

Buds of Claytonia virginica were examined from 9 locations in the metropolitan New York area. A large amount of meiotic irregularity was characteristic of the populations studied. Chromosome counts on pollen mother cells were higher than any reported previously for the taxon, which contains an extensive aneuploid series including at least 40 different numbers ranging from 2n = 12 to ca. 190. In one New Jersey population, plants having approximately 90 chromosomes were associated with those having only 16. All the observations indicated that Claytonia virginica is an unusual species with an ability to tolerate fluctuations in chromosome material without apparent effects on fertility and morphology.
ELECTRON MICROSCOPY OF CARTERIA AND CHLAMYDOMONAS
Authors: Lembi Carole A. , Lang Norma J.
Published: January 2018

Cultures of Chlamydomonas eugametos, Chl. sp., Carteria eugametos, C. crucifera, C. radiosa, and C. sp. were examined with the electron microscope to determine generic differences between Carteria and Chlamydomonas at the ultrastructural level. The ultrastructure of the flagella, mitochondria, dictyosomes, nuclei and ground substance was noted to be similar in all species. The cellular boundary of all species except Chlamydomonas eugametos contains a 250 A intermediate layer of unknown chemical composition between the fibrillar cellulose wall and the outer capsule layer. Four structural features other than the number of flagella distinguish Carteria from Chlamydomonas: the intermediate layer of the cellular boundary, the chloroplast, the pyrenoid and the eyespot. Only in the Carteria species is the intermediate layer traversed by striations or 12‐mμ‐wide bars. Striations in the cellulose wall surrounding the flagellar channels also appear in Carteria eugametos and C. crucifera. The chloroplast lamellae of the Carteria species are grouped into discrete stacks of invaginated thylakoids termed pseudograna. The chloroplast lamellae of Chlamydomonas are broad and sheet‐like and are also invaginated although less frequently than are the pseudograna of Carteria. The phenomenon of infolding of the chloroplast lamellae is suggested as a general developmental process in the formation of new thylakoids. In Carteria, single thylakoids traverse the pyrenoid and there are 2 rows of granules in the eyespot. Favorable micrographs of the eyespot indicate that the granules may be osmiophilic granules of the chloroplast chemically modified for a photoreceptive function.
LIGHT EMISSION FROM THE LUMINOUS FUNGUS COLLYBIA VELUTIPES UNDER DIFFERENT NUTRITIONAL CONDITIONS
Authors: Airth R. L. , Foerster G. Elizabeth
Published: January 2018

Light emission from the luminous fungus Collybia velutipes has been studied under various nutritional conditions and in no instance has growth been obtained with the complete absence of light emission. The effect of varying pH, various nitrogen and carbon sources and the response to different vitamins has been considered. Ammonium‐nitrogen or aspartic acid, glucose and pH 6.0 were shown to be most effective for optimal light emission. This isolate requires the thiazole moiety of the thiamine molecule for light emission; the effects of the thiamine antagonists pyrithiamine and oxythiamine were also studied.
MYCELIUM OF LIMB RUST FUNGI
Authors: Peterson R. S. , Shurtleff R. G.
Published: January 2018

Limb rust is a killing disease of hard pines caused byPeridermiumspp. Study of tissue sections shows that growth of limb rust fungi differs from growth of other plant rusts: (1) longitudinal spread is mainly by hyphal growth within host tracheids; (2) hyphae grow radially in mature xylem, deep in host sapwood; (3) in larger stems mycelia avoid (rather than concentrate in) bark and outer xylem rings; and (4) mycelia become much larger than any previously described for rust fungi. Antibiotics being tested as therapeutants are unlikely to be effective against such deep‐seated mycelia.
NUCLEAR RATIOS AND COMPLEMENTATION IN COMMON‐A HETEROKARYONS OF SCHIZOPHYLLUM COMMUNE
Authors: Snider Philip J. , Raper John R.
Published: January 2018

There are 4 genotypic classes of pairings basic to the tetrapolar, or bifactorial, mating system of the Basidiomycete Schizophyllum commune. One class has a complex phenotype termed “common‐A heterokaryosis.” Analysis shows a high nuclear ratio to be characteristic of this heterokaryon. Selection of the majority type is independent of input nuclear ratio. The common‐A phenotype is interpreted from old and new data to include several major traits: (1) absence of nuclear pairing and conjugate division; (2) extreme variation of nuclear ratio; (3) absence of clamp connections; (4) depression of growth, as measured by rate and final amount dry weight; and (5) usual absence of fruiting. The absence of non‐allelic complementation, previously described as part of the phenotype, has been discounted by new results. The possibility of a quantitative effect of incompatibility remains undecided.
STUDIES OF THE GERMINATION PROCESS IN MELAMPYRUM LINEARE
Authors: Curtis E. J. C. , Cantlon J. E.
Published: January 2018

Seed germination of Melampyrum lineare Desr. requires activation (20 C storage or treatment with gibberellic acid) followed by an extended period of exposure to cold. Without these conditions seeds remain dormant. Seed structure and pattern of development following activation are described. Aseptic culture of embryos excised from dormant seeds showed growth to be possible on agar containing glucose but not on agar containing potato starch. Embryos excised from gibberellin‐activated seeds or embryos growing on agar containing gibberellin grew at the same rate on glucose but could not grow on starch. Thus the gibberellin‐sensitive dormancy mechanism does not involve synthesis or activation in the embryo of starch‐digesting enzymes. This could mean that such a mechanism is located in the endosperm or that the mechanism in Melampyrum is different from that described for barley and for oats
THE RELATIONSHIP OF GELATINOUS FIBERS TO WOOD STRUCTURE IN EASTERN COTTONWOOD (POPULUS DELTOIDES)
Authors: Kaeiser Margaret , Boyce Stephen G.
Published: January 2018

Wood samples from Populus deltoides Marsh. were used to investigate the relationship of gelatinous fibers to the size and number of other wood elements. An increase in the amount of gelatinous fibers was related to a decrease in diameter and an increase in wall thickness of non‐gelatinous fibers. The relative sizes of rays, vessels, and fibers were inter‐related, but all of these wood elements decreased in size with an increase in the amount of gelatinous fibers. Apparently environmental conditions controlling the differentiation of gelatinous fibers also influence the development of associated wood elements. Thus, the adverse physical properties of reaction wood must be attributed to all of these structural differences in the wood and not merely to the presence of large numbers of gelatinous fibers.
MORPHOLOGY OF MARSILEA VESTITA. III. MORPHOGENESIS OF THE LEAVES OF ETIOLATED PLANTS
Authors: Gaudet John J.
Published: January 2018

The laminae of etiolated Marsilea vestita leaves develop by means of marginal meristems. Unlike light‐grown plants, the form of the etiolated plant is not affected by growth on a solid medium. All of the young leaves isolated from light‐grown submerged plants will elongate in darkness. The smallest, etiolated, uncoiled leaves develop into land leaves when they are placed in light, and this development occurs regardless of whether the leaves remain on the plant or are isolated on nutrient agar. Only these smallest leaves (2.3 mm average length) are actually capable of being converted from a submerged leaf form to a land leaf form by darkness.
THE EFFECT OF THE INTERACTION OF TEMPERATURE WITH AFTER‐RIPENING REQUIREMENT AND COMPENSATING TEMPERATURE ON GERMINATION OF SEED OF FIVE SPECIES OF ROSA
Authors: Stewart R. N. , Semeniuk Peter
Published: January 2018

Seeds of 5 rose species, Rosa multiflora Thunb. ‘Cathayensis,’ R. × reversa Waldst. & Kit., R. setigera Michx. ‘Beltsville,’ R. setigera Michx. ‘Serena,’ and R. wichuraiana Crepin, varied in after‐ripening requirement from 30 days at 4.4 C for R. multiflora to 90 days for R. setigera ‘Serena.’ The compensating temperature varied from near 12.8 C for R. × reversa to a value near 29.4 C for R. setigera ‘Beltsville.’ In this report compensating temperature is used to describe that temperature at which mature, moist seed does not germinate, after‐ripening does not take place, and dormancy does not change. Seed germination was reduced by interruption of the after‐ripening period with intervals at temperatures above the compensating temperature. The interruptions were more effective in reducing germination when more frequent and when the temperature during the interval was higher. Species differed in their sensitivity to high‐temperature reduction of germination. Those having the longest after‐ripening requirement were most sensitive. Germination of seeds which had the minimum after‐ripening treatment was repressed more by high temperature than germination of those seeds which had an excess of after‐ripening. The decrease in germination resulted from imposition of a secondary dormancy of the embryo, and probably also from reversal of the after‐ripening effect upon the primary dormancy imposed by the seed coat.
CHLOROPLAST STRUCTURE AND FUNCTION IN CULTURED TOBACCO TISSUE
Authors: Laetsch W. M. , Stetler David A.
Published: January 2018

A comparative study was made of the ability of cultured pith tissue, leaves of buds induced from callus, and mature leaf tissue of Nicotiana tabacum L. ‘Maryland Mammoth’ to fix carbon, as determined by light‐induced C14O2 incorporation. Photosynthetic ability was then correlated with the fine structure of chloroplasts from these tissues. The light to dark incorporation ratio for C14O2 was at least 3 times as great in the leaf tissue as in growing cultured tissue. The chlorophyll content of the leaf tissue was 10 times as great. The carbon fixation pattern of all the tissues, as determined by radioautographs of chromatogramed extracts, was qualitatively the same. The rate of sucrose synthesis differed greatly, since 20% of the total radioactivity of the extracts from mature leaf tissue appeared in sucrose, while only 1.0% was found in sucrose from callus extracts. The incorporation of C14O2 into sugars was inhibited in all the tissue by DCMU (3,4‐dichlorophenyl,1, 1‐dimethylurea). Cultured tissue past the log phase of growth was intermediate between the younger cultured tissue and the leaf tissue in its chlorophyll content and ability to incorporate C14O2 in the light. Proplastids from dark‐grown callus possessed stroma lamellae, but prolamellar bodies were not observed. The chloroplasts from growing callus were partially differentiated in comparison with chloroplasts from mature leaf tissue, since each granum had only 4‐7 lamellae. Chloroplasts from callus past the log phase of growth were indistinguishable from those in mature leaves. This study establishes that the differentiation of chloroplasts in cultured tissue is a function of the growth rate of the tissue. The growth rate and degree of differentiation of the tissue can be regulated, so a well‐defined system is available for the experimental study of chloroplast differentiation.
FLORAL PIGMENTATION STUDIES IN THE GENUS GOSSYPIUM II CHEMOTAXONOMIC ANALYSIS OF DIPLOID GOSSYPIUM SPECIES
Authors: Parks Clifford R.
Published: January 2018

The chromatographic pigment arrays of nine diploid species (G. arboreum, G. anomalum, G. herbaceum, G. stocksii, G. sturtii, G. thurberi, G. gossypioides, G. raimondii and G. klotzschianum) were studied. Among the Old World cottons, G. sturtii of Australia was very different from the species analyzed. The two species of the Herbacea section (G. herbaceum and G. arboreum) were found to have very similar pigment arrays. Both G. anomalum and G. stocksii were more like the Herbacea species than any other species in the genus, but both G. anomalum and G. stocksii had unique pigment characteristics. Although the evidence obtained so far from pigmentation patterns suggests that some pairs of species are closely related, the pigment arrays do not support the classification of the New World diploids into more than one section. From analysis of pigments of interspecific hybrids and their parents, it was found that with a hybrid and one parent species the pigment array of the other parent species could be predicted. Using this approach, the pigment arrays of three New World diploid species were predicted.
ACTION OF PURINE AND PYRIMIDINE ANALOGS ON THE GROWTH AND DIFFERENTIATION OF THE GAMETOPHYTES OF THE FERN ASPLENIUM NIDUS
Authors: Raghavan V.
Published: January 2018

The purine analogs, 8‐azaadenine, 8‐azaguanine, 8‐azaxanthine and 8‐azahypoxanthine, and the pyrimidine analogs, 2‐thiocytosine, 5‐fluorouracil, 2‐thiouracil and 6‐azauracil, inhibited the induction of 2‐dimensional growth in the gametophytes of the fern Asplenium nidus L. In contrast, thymine analogs such as 5‐fluorodeoxyuridine, 2‐thiothymine, 6‐azathymine and 5‐bromouracil caused non‐specific growth inhibitions without suppressing 2‐dimensional growth. Subinhibitory concentrations of 8‐azaxanthine, 8‐azahypoxanthine, and 2‐thiouracil promoted both 1‐dimensional and 2‐dimensional phases of growth of the gametophytes. Inhibitory effects of the analogs were observed on treatment of the spores or of gametophytes of different ages. Gametophytes growing in the analogs for different periods of time recovered from inhibition on transfer to the basal medium.
EFFECT OF CARBON AND NITROGEN NUTRITION ON PLEOMORPHISM IN TRICHOPHYTON MENTAGROPHYTES
Authors: Klein Deana T.
Published: January 2018

Pleomorphism in granular strains of Trichophyton mentagrophytes can be increased or decreased by modifying the nutritional environment. The presence of one of several carbohydrates is necessary and may be the controlling nutritional parameter determining whether or not mutant pleomorphic patches appear, although concentration of the nitrogen source is also important in the pleomorphic response. None of the non‐carbohydrate carbon‐containing compounds tested supported pleomorphism. The activity of any one compound, carbon or nitrogen, appears to be unrelated to the dry weight attainable in the presence of that compound; although a certain level of growth is necessary, it is not a sufficient requisite for pleomorphism. Data presented here give no clue as to the specific grouping or configuration of the carbohydrate which might be required for development of the pleomorphic patch. Some strains develop mutant patches readily when grown at 36 C on a medium containing a suitable source of carbohydrate and nitrogen. Other strains form patches on a more restricted range of these compounds; a few strains show no pleomorphic activity.
STUDIES ON THE GENETIC CONTROL OF RESISTANT SPORANGIUM FORMATION IN ALLOMYCES
Authors: DeLong Sharon K.
Published: January 2018

The diploid sporophyte of the phycomycetous fungus Allomyces arbuscula bears two types of sporangia: thin‐walled, colorless, ephemeral zoosporangia (ZS) and thick‐walled, dark‐brown, resistant sporangia (RS). Normal wild‐type cultures (strain Portugal IE) under standard conditions produce approximately 90% of their total sporangia as RS. These RS give the cultures a dark‐brown color. A mutant was induced with UV irradiation in which the ratio of ZS to RS was shifted so that only 20% of the total sporangia are RS. These cultures are a pale, tan color. Hybrids between the mutants and wild‐types produce ca. 65% RS and are also intermediate in the color of the culture. Meiotic segregation in the RS of the hybrid sporophytes gives gametophytes half of which when selfed produce mutant sporophytes and half of which produce wild‐type sporophytes. The shift from RS to ZS formation is thus considered to be the result of a one‐gene mutation at a locus ‘R.’ The haploid gametophytes of wild‐type strains have in addition to male and female gametangia a small number (2‐4%) of RS. In mutant gametophytes the percent RS has dropped to 0.1‐0.2%. The proposed genotypes at the ‘R’ locus in Allomyces arbuscula are: wild‐type sporophytes (RR), hybrid sporophytes (Rr), mutant sporophytes (rr), wild‐type gametophytes (R) and mutant gametophytes (r).
PERIODIC ZOOSPORE PRODUCTION BY PROTOSIPHON BOTRYOIDES UNDER ALTERNATING LIGHT‐DARK PERIODS
Authors: Stewart James R. , O'Kelley Joseph C.
Published: January 2018

The effect of light‐dark periods, of 24 hr or longer complete cycle, on time of zoospore production by Protosiphon botryoides Klebs was investigated in unstirred flask cultures and in stirred cultures supplied 1% CO2 in air. Synchronized zoospore production was observed in both types of cultures. In stirred cultures supplied 1% CO2 a light‐dark cycle of 36–12 hr gave better synchrony than did a cycle of 12–12 or 60–12 hr. Illumination by cool‐white fluorescent bulbs inhibited zoospore formation strongly, possibly by inhibiting cytoplasmic cleavage in parent cells. Darkness, in comparison to illumination, promoted the formation of zoospores, and their synchronous production under alternating light‐dark cycles occurred as a consequence.
PHOTOPERIODIC ADAPTATION TO LATITUDE IN XANTHIUM STRUMARIUM
Authors: Ray Peter M. , Alexander William E.
Published: January 2018

Photoperiodic responses of collections of Xanthium strumarium L., grown from seed obtained in nature at various localities in North America between latitudes 20° and 45.5° N, were examined. The critical night length was found to vary noticeably with latitude of origin, from about 7.5 hr in the northernmost strains to above 10 hr in the southern strains. These differences are considered to represent genetic adaptation of the reproductive system to environmental variables as a result of natural selection. Several strains showed a quantitative short day response rather than the more usual qualitative response. Strains from Hawaii exhibited a surprisingly tardy and erratic short‐day response with a critical night length of about 11 hr, which may be an adaptation to a tropical climate.
THE ANTHER TAPETUM IN CYTOPLASMIC‐GENETIC MALE STERILE SORGHUM
Authors: Brooks Maegaret H. , Brooks James S. , Chien Lucia
Published: January 2018

Measurements of anthers of five fertile lines of Sorghum vulgare Pers. indicate that the tapetum decreases in radial extent following the two‐celled dyad stage of meiosis. At a mature pollen stage 78% of the anthers of fertile lines and 88% of those of a fertility restorer line have a narrow tapetum measuring between 4 and 16 μ radially, with the remainder having a degenerate tapetum less than 4 μ wide. In isogenic sterile lines, approximately 68% of the anthers have a narrow tapetum less than 16 μ wide at a “prepollen” stage, which represents the terminal stage in the sterile lines, whereas the remaining 32% have a well‐developed or enlarged tapetum measuring over 28 μ in radial width. Tapeta in the sterile lines have a variation in width and in morphology not encountered in fertile lines and presumably display the variable manifestations of nuclear‐cytoplasmic interaction characteristic of cytoplasmic‐genetic male sterility.
EFFECT OF TEMPERATURE ON SEXUAL POPULATIONS OF GONIUM PECTORALE (VOLVOCALES)
Authors: Stein Janet R.
Published: January 2018

Experiments were designed to study the effect of temperature on interpopulation crosses of Gonium pectorale. Both interpopulation and intrapopulation crosses were made at 10, 15, 20 and 25 C. Of the 34 populations studied, one‐third were definitely affected by temperature, showing that temperature is one factor in sexual isolation in at least some populations. Only two populations were completely incompatible with others. In some populations with both mating types, one mating type (the one designated “minus”) was found to be more compatible, possibly reflecting further genetic difference between mating types.