bluuebunny/crossref_metadata_2025 huggingface dataset:
ANATOMY OF THE REPRODUCTIVE BRACTS IN WELWITSCHIA
Authors: Rodin Robert J.
Published: January 2018

Rodin, Robert J. (Calif. State Polytechnic Coll., San Luis Obispo.) Anatomy of the reproductive bracts in Welwitschia. Amer. Jour. Bot. 50 (7): 641–648. Illus. l963.—The anatomy, including venation patterns, of the nodal bracts, sterile cone bracts, and fertile cone bracts of male and female cones is discussed. Two traces which dichotomize are present in each member. Occasional anomalous traces in the perianth have been discovered. Details of sclereids, fibers and gum canals are given. The connate nature of the bracts is described. The homologies of these organs are suggested.
RECOVERY OF NATIVE AND APPLIED AUXIN FROM THE DARK‐GROWN ‘ALASKA’ PEA SEEDLING
Authors: Scott Tom K , Briggs Winslow R.
Published: January 2018

Scott, Tom K., and Winslow R. Briggs. (Stanford U., Stanford, Calif.) Recovery of native and applied auxin from the dark‐grown ‘Alaska’ pea seedling. Amer. Jour. Bot. 50(7): 652–657. Illus. 1963.—The distribution and movement of “free” endogenous and applied auxin were determined in the 7‐day‐old dark‐grown ‘Alaska’ pea epicotyl by means of short‐term ether extraction. A general decrease in total endogenous auxin content took place from apex to base within the growing as well as the non‐growing regions. Factors other than growth itself may be responsible for this decrease. Auxin distribution changes, as they occur following the removal of the apical bud, may reflect an incompletely polar transport system operating in the epicotyl. This suggestion was supported by following the movement of indole‐3‐acetic acid applied in lanolin paste. The results presented are related to similar experiments performed on the light‐grown ‘Alaska’ pea seedling as well as on other vascular plants.
“SORBOSE TOXICITY” IN NEUROSPORA
Authors: Brockman H. E. , de Serres F. J.
Published: January 2018

Brockman, II. E., and F. J. de Serres. (Oak Ridge Natl. Lab., Oak Ridge, Tenn.) “Sorbose toxicity” in Neurospora. Amer. Jour. Bot. 50(7): 709–714. Illus. 1963.—The effect of “sorbose toxicity” on Neurospora conidia or ascospores was compared in sorbose‐fructose‐glucose (S‐F‐G) and sorbose‐sucrose (S‐S) media. Many frequently encountered and difficultly controlled experimental variables may strongly affect viability in S‐S media but are essentially without effect in S‐F‐G media. The viabilities of different mutant strains are affected to varying extents by autoclave exposure time of the S‐S media but not of the S‐F‐G media. Ascospores are more sensitive than conidia to “sorbose kill” in S‐S media. An over plating method described by New meyer (1954) for increasing ascospore “viability” is without effect when sucrose is replaced with fructose and glucose. In all experiments in which sorbose was added to induce colonial growth, “sorbose toxicity” or “sorbose kill” was eliminated or minimized by replacing sucrose with a mixture of fructose and glucose as the carbon source for Neurospora media.
HISTOCHEMICAL LOCALIZATION AT THE ELECTRON MICROSCOPE LEVEL
Authors: Albersheim Peter , Killias Ursula
Published: January 2018

Albersheim, Peter, and Ursula Killias. (Harvard U., Cambridge, Mass.) Histochemical localization at the electron microscope level. Amer. Jour. Bot. 50(7): 732–745. Illus. 1963.—This paper discusses the use of chemical reactions for specifically locating cellular constituents with the electron microscope. Presented in detail are results obtained by using alkaline hydroxylamine and ferric chloride as an electron stain for pectin. This treatment also results in the staining of certain cytoplasmic and nucleolar particles of unknown nature. Also described is the use of bismuth as an electron stain for nucleic acids. A series of micrographs is presented depicting bismuth stained onion root tip cells in various stages of mitosis.
INDUCTION OF WOUND‐VESSEL DIFFERENTIATION IN ISOLATED COLEUS STEM SEGMENTS IN VITRO
Authors: FOSKET D. E. , ROBERTS LORIN W.
Published: January 2018

Excised internodes and 2‐mm‐thick transverse stem segments of Coleus blumei were incubated 7 days on media containing 2% sucrose, 1% agar, and various growth substances. Wound‐vessel members differentiated in the 2‐mm‐thick tissue slices incubated on medium containing no exogenous auxin (control). Compared to control slices, the addition to the medium of either IAA (50 or 5 ppm), 2, 4‐D (10, 1, or 0.1 ppm), TIBA (50, 5, or 0.5 ppm), or kinetin (50, 5, 0.5 or 0.05 ppm) inhibited wound‐vessel differentiation. Simultaneous treatment of tissue slices with IAA and kinetin inhibited wound‐vessel differentiation, as did the incubation of tissue slices on medium containing no sucrose. Low concentrations of IAA (0.05 ppm) or 2, 4‐D (0.01 ppm) resulted in over a 100% increase in the numbers of wound‐vessel members differentiated. These results are interpreted as indicating auxin synthesis by the tissue slices and the participation of auxin as a limiting factor in xylogenesis. The inhibition of wound‐vessel differentiation by relatively high concentrations of 2,4‐D, TIBA, or kinetin is interpreted as a reflection of the inhibition of polar auxin transport by these substances, and an indication that polar auxin transport enhances xylogenesis.
COMPARATIVE MORPHOLOGY OF THE CARPEL IN THE ROSACEAE. I. PRUNOIDEAE: PRUNUS
Authors: Sterling Clarence
Published: January 2018

A study of the carpel in 27 species of Prunus has shown certain notable structural relationships associated with the extent of closure of the carpellary margins. These relationships involve the degree of fusion of the 2 integuments, the number of vegetative bundles in the base of the carpel, the extent of fusion of the ovular bundles with one another and with the wing bundles, the relative size of the ovular bundles, and the relative development of the central vascular plexus. The comparative evidence strongly supports a primitively separate state of ovular and vegetative bundles. The significance of this finding is discussed.
INHIBITION OF CELL PROLIFERATION AND EXPANSION IN VITRO BY THREE STEM GROWTH RETARDANTS
Authors: Sachs R. M. , Wohlers Mary Ann
Published: January 2018

Three inhibitors of stem elongation, Amo, CCC, and Phosfon, inhibit cell division and expansion in tissues cultured in vitro. However, contrary to the case in intact plants, gibberellic acid does not prevent the retardant‐induced inhibition in vitro. Supplementary auxin is also without effect in preventing the inhibition. Thus, the effect of the retardants cannot be simply that of inhibiting gibberellin or auxin synthesis. With respect to growth, carrot, chrysanthemum, and geranium tissues are equally sensitive to all 3 retardants, whereas tobacco tissues are considerably more resistant to Amo and apparently unaffected by CCC.
A STUDY OF A NEW SPECIES OF SPONGIOCHLORIS INTRODUCED INTO STERILE SOIL
Authors: Trainor F. R. , McLean R. J.
Published: January 2018

A new species of Spongiochloris, S. typica, was isolated from a Connecticut soil. It can be distinguished from other species by the presence of many pyrenoids; by the cell size of light‐grown cells (up to 80μ), usually with thin walls; and by the vacuolate older cells. Zoospores present favorable material for observation of withdrawal of flagella upon quiescence. The organism was reintroduced into sterile soil, the soil was then air‐dried, and the viability of the organism in soil was measured during 1 year. Each month, a 0.5‐g sample of soil was heated at 100 C for 1 hr prior to incubation in basal medium; a control sample was incubated, along with the treated soil, in continuous illumination. By means of 10‐fold dilutions of such cultures, it was determined that more than 10,000 cells per 0.5 g of soil survived heat pretreatment and more than 100,000 cells per 0.5 g were viable in the desiccated soil after 1 year.
ONTOGENY AND DIFFERENTIATION OF SCLEREIDS IN RAUWOLFIA
Authors: Mia Abdul J.
Published: January 2018

An interesting anatomic feature of Rauwolfia is the occurrence of a remarkable type of sclereid in the stem and root. The initials of the sclereids in the stem arise in the ground tissue element of the pith in a region between 50 and 70μ below the surface of the shoot apex. This region of the shoot remains surrounded by a whorl of either 3 or 4 leaves. Sclereids initiate in succession in association with each whorl of leaves. Thus, the sclereids are restricted to the nodes. The sclereids in the stem arise as a primary element of the shoot from the ground tissue of the pith. In the root, they differentiate from the cells of the phelloderm and are secondary in origin. Morphologically, the sclereids in these 2 organs are basically the same, except that the sclereids in the stem are larger in size than those in the root. A solitary cell, or 2 to several cells in a longitudinal cell file (originated from a single mother cell), may differentiate into sclereid initials. The growth of the sclereids through relatively compact ground tissue of the pith is possibly accomplished by a combination of gliding growth and apical intrusive process. The sclereid initials grow rapidly and force their way between the parenchymatous cells. As a result, the neighboring cells lose their original surface contacts. Sclereids increase in size rapidly, and, therefore, very enlarged sclereids with thin primary walls may be observed in the second node. They mature progressively in basipetal direction in the subjacent nodes. In the fifth or sixth node, mature sclereids with massive secondary walls are most common. The secondary walls of sclereids contain much lignin as determined by the phloroglucinol‐HCl test. The walls of sclereids at maturity show a variable number of lamellae ranging from 10 to 15 in the lateral walls. A remarkable feature of the sclereids is their canal‐like pits in the secondary walls. Two adjacent pits may coalesce uniquely to form a Y‐like configuration directed centrifugally from the lumen of the sclereids. The sclereids are ventrically symmetrical, joined end‐to‐end by their transverse walls like 2 superimposed young fibers.
IDENTIFICATION OF MONOSOMES FOR SIX CHROMOSOMES IN GOSSYPIUM HIRSUTUM
Authors: Endrizzi J. E. , Brown Meta S.
Published: January 2018

Six primary monosomes of the amphidiploid species Gossypium hirsutum have been identified as separate chromosomes of the complement. On the basis of cytogenetic tests involving translocations, a diploid species of the D genome group, and genetic markers, 4 of the 6 monosomes were designated chromosomes 1, 2, 4 and 6 of the A subgenome and 2 were designated chromosomes 17 and 18 of the D subgenome. Fourteen other monosomes were identified as duplicates of 3 of the above 6 primaries.
MORPHOLOGY OF TRICHOMETASPHAERIA TURCICA
Authors: Luttrell E. S.
Published: January 2018

Ascocarps of Trichometasphaeria turcica Luttrell originated in culture as globose parenchymatous stromata within which ascogonia differentiated. As the ascostroma enlarged, stromal cells immediately above the ascogonium produced hyphal outgrowths whose tips grew downward and intertwined beneath the ascogonium. Intercalary growth of these hyphae formed a pseudoparaphysate centrum. Ascogenous hyphae near the base of the centrum produced bitunicate asci which grew upward among the persistent pseudoparaphyses. The ostiole was a broad pore resulting from dissolution of the peripheral stromal cells above the apex of the single locule. Spiny outgrowths from the peripheral cells surrounded the ostiole. The bitunicate asci and ascostromatic ascocarps place this fungus in the subclass Loculoascomycetidae. The pseudoparaphysate centrum and perithecioid ascostroma are characteristic of the Pleosporales. The apparently insignificant character of a protruding conidial hilum was the only essential feature distinguishing Helminthosporium turcicum Pass., the conidial stage of T. turcica, from H. maydis Nisik. & Miyake, a typical representative of species of Helminthosporium with perfect stages in Cochliobolus.
FOUR BASIC QUESTIONS OF PLANT BIOLOGY
Authors: Stebbins G. Ledyard
Published: January 2018

The 4 questions discussed are the nature of life, the mechanism of heredity, the mechanism of development, and the problem of evolution. The basic property of life is organization, but no single property, present in all living things, distinguishes them from nonliving systems. Life results from integration of various properties, which at the individual level are principally replication of specific substances and response to stimuli, but at the level of the population in time the most significant property of life is its ability to generate unpredictable systems of variability. Heredity is determined primarily by the DNA‐RNA‐protein system, which must be regarded as a single functioning unit, since its elements are functionless when separated from each other. In addition, 4 different kinds of mechanisms for regulating gene action are postulated. Our full understanding of heredity must include a thorough knowledge of these mechanisms, as well as of the reasons why organisms differ in base pair composition of their DNA, and in the total amount of DNA present in the nucleus. Development in higher plants does not involve changes in basic heredity, but rather semi‐permanent alterations in the physicochemical conditions of cells. Modern research on cell, tissue, and organ culture is beginning to elucidate the nature of these alterations, and to relate them to gene‐controlled enzyme activity. The translation of physicochemical differences in cells to morphogenetic behavior is principally via 4 processes, which are beginning to be understood: differential rates of cell division and cell enlargement; orientation of the mitotic spindle by cell shape, cell growth, and cytoplasmic structure; intracellular polarization of cytoplasmic elements followed by differential mitosis across the gradient thus produced; and intercellular induction of mitosis. In regard to evolution, the basic processes controlling it have been identified and are reasonably well known. Future research should be on the nature of hybrid inviability and sterility, the comparative evolution of genetic systems, and the question of whether new morphological characteristics require the origin and activity of genes with new enzymatic activities, or are brought about by repatterning previously existing sequences.
CHARACTERIZATION OF DEVELOPMENT IN MAIZE THROUGH THE USE OF MUTANTS. I. THE POLYTYPIC (Pt) AND RAMOSA‐1 (ra1) MUTANTS
Authors: Postlethwait S. N. , Nelson O. E.
Published: January 2018

The origin of morphological differences attributable to mutant genes can be identified at certain switch points in the developmental pathway. The effect of the Polytypic (Pt) gene is a stimulus to meristems in the developing inflorescence to continuous initiation of differentiating structures. The most severe expression is a suppression of meristematic activity. The action of the gene is a superimposition of its effect on the normal developmental pathway. The ramosa‐1 (ra1) gene interrupts the normal sequence of events, at the switch point, which would normally result in spikelet formation, and there is produced instead a lateral branch. The response of numerous switch points in the developmental pathway of the maize inflorescence supports the conclusion that meristems are a plastic system genetically programmed at successive intervals.
MORPHOLOGY AND GENETICS OF A PERIODIC COLONIAL MUTANT OF NEUROSPORA CRASSA
Authors: Sussman Alfred S. , Lowry Robert J. , Durkee Thomas
Published: January 2018

A mutant of strain 69–1113a of Neurospora crassa, which shows periodic growth upon both complete and minimal media, was named “clock,” and some of the morphological and genetic differences between this mutant and the “patch” and “wild” strains were investigated. In contrast to the uniform growth of “wild,” the “clock” mutant produces a series of bands formed by cymelike aggregations of hyphae which become progressively more dense and finally mark the end (front) of a growth band. A new growth band is formed by a number of hyphae which grow out as in “wild” strains and dichotomize and form new cymes which again become progressively more dense and finally form a new front. It is shown that “clock” continues its rhythmic growth when cultured in continuous darkness. Some “wild” strains were induced to grow periodically on appropriate media. A medium containing equal quantities of sorbose and sucrose caused strain 65–811A (a “wild”) to produce the “patch” type growth. Random isolation, as well as ordered isolation, of ascospores following a cross between “wild” and “clock” show a 1: 1 segregation indicating that “clock” differs from “wild” by a single gene.
DOSAGE EFFECTS OF THE LANCEOLATE GENE IN TOMATO
Authors: Stettler Reinhard F.
Published: January 2018

In contrast to the odd‐pinnately compound leaf of the normal (+/+) tomato plant (Lycopersicon esculentum), the single‐gene mutant lanceolate (La/+) generally has a simple leaf. Lanceolate plants, also, have small fruits and flowers, weak apical dominance, and exhibit variation in the position and fusion of cotyledons. Homozygous mutants (La/La) appear in 3 different phenotypes, 1 of which, narrow, has narrow simple leaves, sterile inflorescences, and extremely weak apical dominance. The other 2, modified, and reduced, lack an organized shoot. After selfing La/ + plants for 9 generations, autotetraploids were produced with the aid of colchicine. In addition, several triploid plants arose spontaneously. The study of diploid, triploid, and tetraploid material with various proportions of the La allele revealed in many characters a graded series as a function of the La dosage. With increasing La dose, there was a gradual reduction in: (1) total leaf length; (2) the number and size of primary and secondary lateral leaflets; (3) the number and size of marginal lobes of the terminal leaflet, associated with an increase in the proportional length of the terminal leaflet. Many leaves were found with the basal lobes of the terminal leaflet resembling incompletely separated lateral leaflets. The differences in leaf shape between different genotypes came about before the leaf primordium was 3 mm long. There was a progressive delay in the initiation of lateral primordia with increasing La dosage. It is proposed that the gradual changes from compound to simple leaves with increasing La dosage are produced by successively greater restrictions of meristematic activity after the terminal leaflet is formed. With increasing proportion of La alleles, the reproductive structures showed: (1) a decrease in the number of flowers per inflorescence; (2) a decrease in the length of the sepals; (3) an increase in the proportion of flowers with dialytic anthers. Dialytic anthers had narrow adaxial lobes and were frequently twisted along their main axes. The common denominator for most trends affected by the La allele seems to be a general reduction of growth, but more so in lateral than in longitudinal growth. Histological data suggest that the reduction in lateral growth is mainly brought about by a reduction of cell division in lateral meristems.
ADVENTIVE EMBRYONY IN TISSUE CULTURES OF THE WILD CARROT, DAUCUS CAROTA
Authors: Halperin W. , Wetherell D. F.
Published: January 2018

Cultures of callus tissue derived from roots, petioles, or umbellet peduncles of the wild carrot have been observed to form large numbers of adventive embryos which closely resemble ovular embryos of the same species. In the presence of cocoanut milk, which is not otherwise required in the nutrient medium, these embryos germinate and produce plants which may be normal in all respects. The sequence of forms in embryogenesis has been traced back to embryos of fewer than 10 cells, and the pattern of development has been found in many cases to correspond closely to that of ovular embryos, especially with respect to the early filamentous stages. The accumulation of granular starch in both the parenchymatous cells of the callus and in the embryos at certain stages of their development is a marked characteristic of differentiating callus. Investigation of the nutrient requirements of the callus tissue undergoing differentiation of embryos reveals that a wide latitude is possible in the composition of the basal medium, consisting of mineral salts, vitamins, and sucrose. Embryos form readily in tissue which has been extensively subcultured on a simple defined medium which consists of the basal medium plus adenine and 2,4‐D. Tissues cultured on cocoanut milk and 2,4‐D, or kinetin and 2,4‐D, are more heterogeneous in composition and may contain, in addition to embryos, idioblastic tracheids, anthocyanin‐pigmented cells, and complex vascularized nodules. Chemical control of alternative morphogenetic pathways, and of embryogenesis itself, is partially demonstrable.
CHROMOSOME NUMBERS IN SINGLE CELL CLONES OF TOBACCO TISSUE
Authors: Cooper Lillian S. , Cooper D. C. , Hildebrandt A. C. , Riker A. J.
Published: January 2018

Two clones of tissue of single‐cell origin isolated from crown gall callus of Nicotiana tabacum were examined cytologically. Both clones had been grown on the same medium under the same conditions for 8 years. Chromosome counts of 110 polar views of metaphase plates revealed chromosome numbers of 48, 96, and 192 in both clones, the majority having 48. The nucleus of the original cell from which each clone was grown must have possessed 48 chromosomes. The polyploidy which developed may be ascribed to wounding, to the constituents of the culture medium, and/or to abnormal mitoses.
THE DESTRUCTION OF XYLEM BY A PLASMODIAL PARASITE IN SEEDLINGS OF PISUM SATIVUM
Authors: Sorokin Helen P.
Published: January 2018

The seedlings of Pisum sativum var. ‘Alaska’ grown either in complete darkness or in partial red light are often afflicted by a plasmodial parasite, which either partially or completely destroys the tracheids. The vegetative stage of the organism consists of small cells connected with each other by hyaline filaments. These cells are seen inside the tracheids, where they presumably hydrolyze cellulose to separate the lignified helical wall thickenings from the cell wall. The spirals are then incorporated into a plasmodium. The plasmodia are found both inside and outside the plant tissue. The younger portions of the seedlings often contain large plasmodia with engulfed helical wall thickenings, which are gradually dissolved, presumably by means of a peetinolytic enzyme, at the time of sporulation. The spores (4–5μ) are borne in small numbers, ca. 10–16 per well‐defined oval or elongate sporangium. The pitted vessels are not destroyed by the organism. Pea seedlings can be badly infected without showing externally visible pathology. Unless the xylem is destroyed and the plant tissues are filled with plasmodia, recovery from the infection is possible. Pisum sativum, a homozygous variety ‘L’ grown aseptically in light on an agar medium, also contained all the stages in the development of this organism.
FURTHER STUDIES IN MULTIPLE ALLELOMORPH HETEROTHALLISM IN THE MYXOMYCETE DIDYMIUM IRIDIS
Authors: Collins O'Neil Ray , Ling Hubert
Published: January 2018

Analysis of an isolate of Didymium iridis from Costa Rica indicates that it possesses a pair of incompatibility factors. These factors have been shown to be allelic with those of a Honduras and a Panama isolate. Data presented in this paper show that, among them, the 3 isolates possess 6 incompatibility alleles at 1 locus.
POLYPLOIDY IN THE BASIDIOMYCETE CYATHUS STERCOREUS
Authors: Lu Benjamin C.
Published: January 2018

Chromosome analysis of the basidiomycete Cyathus stercoreus (Nidulariaceae) reveals that certain chromosomes of the haploid complement structurally resemble one another. These like chromosomes exhibit with high frequency a tendency to form quadrivalents or to show secondary association at diplotene and diakinesis of meiosis, suggesting some degree of homology. This indicates that C. stercoreus is a tetraploid species. It is suggested that the polyploidy of the present species may have resulted from allotetraploidy involving species which may have been evolved from a single ancestor.
THE BASIDIA OF EXIDIA NUCLEATA. II. DEVELOPMENT
Authors: Wells Kenneth
Published: January 2018

The basidia of Exidia nucleate, were studied by light and electron microscopy. The basidium arises from a basal clamp‐connection as a subcylindrical, dikaryotic structure but soon becomes sphaeropedunculate. Mitochondria, endoplasmic reticulum, and compact lamellar systems are more abundant and more evenly dispersed in diploid probasidia than in dikaryotic probasidia, whereas vacuoles in the apical regions are larger in dikaryotic probasidia. Oil globules are few or absent in the earlier stages but increase in size and number throughout basidial development. Karyogamy results in a diploid nucleus approximately twice the volume of haploid nuclei. Although indications were noted of reorganization of the nuclear envelope during the terminal stages of reduction division, available evidence does not suggest a prolonged loss of the nuclear envelope during division. Internal wall formation is centripetal, at least in those stages observed. In areas of active wall formation, a conspicuous zone devoid of mitochondria, oil globules, and endoplasmic reticulum was noted consistently. The circumscribing wall of a hypobasidial segment is composed of 2 lamellae of contrasting electron‐density and is separated from the walls of adjacent hypobasidial segments and the wall delimiting the enucleate stalk by a median electron‐transparent lamella. Although extensive vacuolation occurs in the hypobasidial segments as the nuclei and most of the cytoplasm pass through the epibasidia into the basidiospores, evidence of active nuclear migration was observed. Each basidiospore contains a nucleus, mitochondria, endoplasmic reticulum, and numerous oil globules.
A LIGHT AND ELECTRON MICROSCOPE STUDY OF INTERLAMELLAR POLYGLUCOSIDE BODIES IN OSCILLATORIA CHALYBIA
Authors: Giesy Robert M.
Published: January 2018

A light and electron microscopic study of interlamellar granules in Oscillatoria chalybia was made to determine their physiological nature. Oscillatoria chalybia was cultured under continuous light in media of high nitrogen content, moderate nitrogen content and low nitrogen content. Cultures growing vigorously in a medium of moderate nitrogen content were placed in darkness for an additional 96 hr. Periodic acid‐Schiffs reagent tests were made on specimens from these 4 cultural conditions. Electron microscopic studies of interlamellar granules were correlated with the cytochemical tests. It is shown that diastase digestion will eliminate the PAS‐positive substance and the interlamellar granules. Conclusions are that the interlamellar granules are polyglucoside in nature and that they vary in number and size with available nitrogen, light intensity and age of culture in such a way as to indicate that they are food reserves.
PYRENOIDS, RAPHES, AND OTHER FINE STRUCTURE IN DIATOMS
Authors: Drum R. W. , Pankratz H. S.
Published: January 2018

Pyrenoids of 6 diatoms, Acnanthes minutissima, Cyclotella meneghiniania, Cymbella affinis, Gomphonema parvulum, Nitzschia sp., and Surirella ovalis, were examined comparatively with the electron microscope. All except those of G. parvulum were membrane‐limited. The pyrenoid membrane forms a ridge around the pyrenoid of S. ovalis, C. meneghiniania, and Nitzschia sp. Distended double‐disc bands cross the pyrenoids of C. affinis, G. parvulum, S. ovalis, and A. minutissima; single‐disc bands occur in C. meneghiniania, and 3 disc bands in Nitzschia sp. The raphe fissures of A. minutissima, Nitzschia sp., and S. ovalis did not contain any cytoplasm or obvious organs of locomotion. In G. parvulum, membranous profiles extend outward from the raphe fissure, but these probably are not responsible for movement. In this diatom 2 membranes usually cross the raphe, and the distance between them fluctuates indicating that they may undulate to force water through the raphe. A 7–10 mμ subfrustular zone is associated with the inner surface of the silica, but separate from the cytoplasmic membrane, in Nitzschia sp. and G. parvulum. In the latter, it is attached to siliceous knobs protruding from the inner surface of the silica. It may join the 2 halves of the frustale, which are otherwise not connected either to each other or to the cytoplasm. Pores 80–100 mμ in diameter occur in the nuclear envelopes of all diatoms examined. Dictyosomes are always perinuclear. In S. ovalis the vesicular complex is a convoluted, single‐membrane‐limited structure containing a variety of vesicular profiles, and occupying much of the central cytoplasm. Internally it resembles leucosin bodies of a chrysophyte, but the arrangement and morphology of the internal vesicles suggests that intracellular pinocytosis may occur.
PHOSPHATASE ACTIVITY AND CELLULAR DIFFERENTIATION IN PHLEUM ROOT MERISTEM
Authors: Czernik Carol A. , Avers Charlotte J.
Published: January 2018

Using 9 different organic phosphate substrates as alternatives in a standardized 5′‐nucleotidase histochemical test system, enzyme activity patterns were recorded for timothy grass root epidermis. At least 4 different phosphatases were distinguished on the bases of substrate specificity, reaction rate, tissue distribution, and response to inhibitors. Except with adenosine‐3′‐monophosphate, all activities were restricted to the 300‐mμ‐long root tip meristem. These enzyme activities were associated with the earliest phases of differentiation of the epidermal hair and hairless cell initials. The distribution of activities was not associated with the same cell type in each part of the meristem. Little activity was found with most substrates in the undifferentiated cells of the 0‐100μ zone; alternating active hairless and inactive hair cell initials predominated in the 100‐200μ segment; and active hair–inactive hairless sister cells formed the principal pattern in the 200‐300μ segment of the meristem. The data showed that a particular enzyme activity was associated with a specific cell type only in relation to that cell's position along the differentiation gradient of the entire tissue. But, within a meristem segment, a specific cell type might act differently from its neighbors, depending on its mitotic capacity. This complex of physiological dependence and independence of a cell type on tissue ontogeny was cited as a characteristic of the phenomenon of cellular differentiation superimposed on tissue differentiation gradients.
ENGULFMENT AND ANASTOMOSIS IN THE CELLULAR SLIME MOLDS (ACRASIALES)
Authors: Huffman D. M. , Olive L. S.
Published: January 2018

Evidence for engulfment and anastomosis of the myxamoebae of several members of the Acrasiales is presented. Photomicrographic evidence for engulfment and anastomosis indicates that these processes are unrelated to any regular sexual mechanism. Vacuolar activity was found to be associated with plasma membrane properties in both anastomosis and engulfment. Frequent multiple engulfment, progressive destruction and digestion of the ingested cells, and ultimate egestion of both intact and partially digested engulfed cells are interpreted as evidence favoring the view that engulfment is a cannibalistic activity. Binucleate and multinucleate amoebae were produced by cell fusion; however, no supporting evidence for nuclear fusion was obtained from observations of either anastomosis or engulfment. It is concluded that no regular sexuality occurs in the usual life cycle of the Acrasiales.
MORPHOLOGY OF MARSILEA VESTITA. I. ONTOGENY AND MORPHOLOGY OF THE SUBMERGED AND LAND FORMS OF THE JUVENILE LEAVES
Authors: Gaudet John J.
Published: January 2018

During their ontogeny, the primordia of the juvenile leaves of Marsilea plants in sterile culture develop 1, 2 or 4 marginal meristems, and these, in turn, contribute cells to the young leaf by anti‐ and periclinal cell divisions. The final leaves are unifid, bifid, or quadrifid, depending on how many marginal meristems develop, and this is determined early in the ontogeny of the leaf. The mechanism which determines whether or not a marginal meristem develops may fluctuate, as shown by the existence of trifid leaves. Two forms of juvenile leaves are produced, those in a liquid medium, which in many respects resemble the adult quadrifid submerged leaves, and those on a solid medium, which in many respects resemble the adult land leaves.
NOTES ON SOME GRASSES. XVI. EMBRYO STRUCTURE OF THE GENUS ORYZA IN RELATION TO THE SYSTEMATICS
Authors: Tateoka Tuguo
Published: January 2018

Three distinct types of embryo have been found in 18 species of the genus Oryza. Type 1 is characterized by lateral fusion of the epiblast and the scutellum and also by the development of auricles. Type 2 has no auricle, and the epiblast is not laterally fused with the scutellum. Type 3 has a cleft between the lower part of the scutellum and the coleorhiza, a long epiblast which is free from the scutellum, and lacks auricles. Type 1 has been found in 13 species of section Sativae, Type 2 in 4 species of sections Granulatae and Coarctatae, and Type 3 in O. coarctata only. The results indicate that species of section Sativae are more or less closely related, while section Coarctatae is a heterogeneous group. A new section, Ridleyianae, has been described for Oryza ridleyi and some other species. Oryza coarctata has unique features in embryo structure, morphology and leaf anatomy, and this species has been moved from the genus Oryza to a separate genus, Sclerophyllum, which is here revived.
CALLOSE SUBSTANCE IN SIEVE ELEMENTS
Authors: Evert Ray F. , Derr William F.
Published: January 2018

The secondary phloem of 6 species of woody dicotyledons was examined for the occurrence of callose on the sieve plates of active sieve elements. Fluorescence and bright‐field staining methods were used to detect callose. Tissue from the 6 species was killed and fixed in each of 5 solutions. Some tissue of each species was submerged in the killing solutions as quickly as possible, the remainder within 15 min after removal from the tree. In each species, some active sieve elements of the quick‐killed tissue gave negative callose reactions. All active sieve elements of the delay‐killed tissue gave positive callose reactions. These and other results suggest that the active sieve elements in the secondary phloem of the species studied normally lack callose and that the extent of callose deposition in these cells depended primarily upon the rapidity with which the sieve‐element protoplasts were killed after wounding of the phloem. In addition, bright‐field observations of sieve plates of large numbers of sieve elements from a seasonal collection of Tilia americana secondary phloem suggest that the active sieve elements normally lack callose during the growing season and that the inactive sieve elements normally possess it (dormancy callose).
HYBRIDIZATION STUDIES IN PERENNIAL ZINNIAS
Authors: Torres Andrew M.
Published: January 2018

Results of hybridization studies among the 6 species of subgenus Diplothrix (Zinnia‐compositae) are reported. Also included are analyses of chiasmata frequency in the parental species and 2 diploid hybrids. Pairing relationships and chiasmata frequency of the chromosomes in the hybrids of the diploid species indicate their genomes are homologous. Analyses of F2's of Z. juni‐perifolia X acerosa (2n) show that production of pigment in ray flowers, C, from Z. juniperifolia segregates as a simple dominant over colorless, cc, from Z. acerosa. Morphological studies of the hybrids produced to date indicate that the origin of the polyploid taxa has been more circuitous than simple hybridization followed by chromosome doubling. The genomic constitution of Z. juniperifolia is designated A1A1, that of Z. acerosa A2A2, and that of Z. oligantha A3A3. Morphological data and chromosomal pairing in the polyploid hybrids suggest that the tetraploid species should be tentatively assigned genomic formulae as follows: A1A1A2A2 or A1A1A3A3 for both Z. citrea, and Z. grandiflora, and A2A2A3A3 for 4n Z. acerosa.
THE CACTUS GYNOECIUM: A NEW INTERPRETATION
Authors: Boke Norman H.
Published: January 2018

Although taxonomists interpret the ovaries of most cacti as inferior,3 the inferior position has been derived in a very different manner from that in most flowering plants. In the classical situation, the dorsal sides of connate carpels arc invested by a floral tube (hypanthium) ; in Cactaceac, on the other hand, the dorsal sides of the carpels are mostly free—not invested by a floral tube. The ventral sutures are pulled downward during formation of the hollow receptacle so that they come to lie on the sides of a locule between flanges of tissue which represent the reduced remains of fused margins and lateral walls of adjacent carpels. The morphology of an individual carpel is like that of a pea pod which has been split midway between dorsal and ventral bundles, then opened up so that the dorsal segment projects upward, the ventral segment containing the ovules, downward. In most cacti, the ventral segments are adnate to the walls of a hollow floral receptacle. In all cases observed so far, the floor of the locule appears not to be invested by carpellary tissue—it is interpreted here as representing free recoptacular tissue. In other words, the morphological bases of cactus carpels are not at the bottom of the locule, but above it, where the dorsal and ventral bundle systems diverge from the recurrent receptacular bundles. This interpretation, like the more complex one offered by Buxbaum, explains the commissural stigmas reported by Tiagi for Opuntia and Mammillaria.
A CHROMATOGRAPHIC STUDY OF THE PHENOLICS OF SPECIES OF LOTUS CLOSELY RELATED TO L. CORNICULATUS AND THEIR TAXONOMIC SIGNIFICANCE
Authors: Harney Patricia M. , Grant William F.
Published: January 2018

The incidence of flavonoids and phenolic acids substantiates the reclassification of a number of diploid taxa formerly considered as varieties of the tetraploid species, L. corniculatus. Whereas leaves of L. corniculatus contained leucodelphinidin, quercetin, leucocyanidin, kaempferol, p‐coumaric acid and ferulic acid, those of the diploid species, L. alpinus, L. japonicus, L. krylovii and L. schoelleri, lacked leucodelphinidin but contained sinapic acid which was rarely found in leaves of L. corniculatus. The leaves of L. filicaulis contained the same compounds as those of the aforementioned diploid species but lacked sinapic acid. Lotus tenuis and L. borbasii differed most from L. corniculatus in that their leaves possessed only kaempferol and ferulic acid. The morphological polymorphism evident in plants of L. corniculatus was not reflected in the flavonoid and phenolic acid content of this species. The data obtained lend support for the hypothesis of an allotetraploid origin for L. corniculatus. The phenolic content of the leaves of interspecific hybrids between diploid species was a summation of the phenolic residues found in the parental species. The same is true of the plants of an F2 population of a cross between L. japonicus and L. filicaulis. The results indicate that phenolic compounds in the leaves of Lotus are inherited in a dominant fashion and that they may be used as species characteristics in systematic studies. Lotus caucasicus has been determined to be a tetraploid species with 24 somatic chromosomes.
DEVELOPMENTAL MORPHOLOGY AND CYTOLOGY OF BOLDIA ERYTHROSIPHON
Authors: Nichols H. Wayne
Published: January 2018

The ontogenetic development, cytology, and life history of the freshwater red alga Boldia crythrosiphon has been studied over a 3‐yr period. The alga reproduces by monospores which are formed singly or in sori from a saccate, tubular thallus. These monospores reconstitute the erect saccate thallus or divide to form a prostrate stage which also reproduces itself by monospores or divides in several planes to re‐form the saccate thallus. The chromosome number of Boldia erythrosiphon is 8 ± 1. The saccate thallus is discussed in relation to plant body types among other red algae.
CYTOPLASMIC EFFECTS ON THE DIFFERENTIATION OF ANTHERS AND OVULES OF COTTON
Authors: Meyer Vesta G. , Meyer James R.
Published: January 2018

Reciprocal crosses of Upland cotton with a hybrid derived from (Gossypium anomalum × G. thurberi) × G. hirsutum produced progenies differing significantly in anther development and in the production of supernumerary ovules outside the ovary. Plants with G. anomalum cytoplasm produced fewer anthers than the reciprocal hybrids with G. hirsutum cytoplasm, had a higher percentage of sterile anthers, and were far more likely to form external ovules on an abnormally thickened tip of the staminal tube. The number of locules and ovules within the ovary was not significantly affected by cytoplasm.
COMPARATIVE MORPHOLOGY OF THE CARPEL IN THE ROSACEAE. III. POMOIDEAE: CRATAEGUS, HESPEROMELES, MESPILUS, OSTEOMELES
Authors: Sterling Clarence
Published: January 2018

The carpels in Crataegus, Hesperomeles, Mespilus, and Osteomeles appear to constitute a morphologically related group: all have bony pits, ovules that tend to be acollateral (usually superposed), and clearly separate ovular and wing bundles, i.e., no “ventral” bundles, at the level of ovular insertion. In species whose carpels have no sutural opening, the integuments are more extensively fused with one another, the degree of intercarpellary fusion tends to be greater, and the carpels are fused with the floral cup to relatively higher levels than in those species whose carpels have a sutural opening. In the few cases in which wing and ovular bundles are adnate at the locular base (Crataegus monogyna, Mespilus, Osteomeles anthyllidifolia, O. Schwerinae), the extent of inter‐ and extracarpellary fusion and sutural closure is among the most advanced.
THE INFLUENCE OF CULTURAL CONDITIONS ON THE INDUCTION OF APOGAMY IN PTERIDIUM GAMETOPHYTES
Authors: Whittier Dean P.
Published: January 2018

Apogamous sporophytes formed on Pteridium gametophytes in response to concentrations of certain sugars which supported gametophytic growth. High osmotic concentration of the medium inhibited apogamy, while variations in the basic medium were not stimulatory. Agar, autoclaving, the ammonium ion, and dry media were not required for apogamy. Renewing the medium during an experiment enhanced the apogamous response. Changing the medium at set intervals facilitated the separation of apogamous plant development into gametophytic, initiative, and developmental phases, thus enabling testing of various factors at each of these stages. Apogamy was light‐initiated, while the actual development of apogamous sporophytes was caused by light, succinic acid or sugar.
LEACHING OF METABOLITES FROM FOLIAGE AND SUBSEQUENT REABSORPTION AND REDISTRIBUTION OF THE LEACHATE IN PLANTS
Authors: Tukey H. B. , Mecklenburg R. A.
Published: January 2018

Inorganic and organic metabolites, including carbohydrates, amino acids, and organic acids, may be leached from the foliage of 125 diverse plant species by the action of rain, dew, and mist. Ca45, P32, and Sr89 absorbed by roots, and C14 absorbed as C14O2 by foliage were leached from squash leaves and were subsequently reabsorbed by the roots and translocated to the aboveground parts of several plant species. This phenomenon of nutrient recycling is apparently a widespread natural phenomenon and has implications in plant nutrition. Bean plants were grown through 1 complete generation on the leachates from squash leaves. Leaching and reabsorption of the leachates are important in the distribution of fallout products, in the stimulation and suppression of plants beneath the spread of other plants, in plant competition, and in the development of plant associations.
APPLICATION OF THE 22.5 MEV DEUTERON MICROBEAM TO THE STUDY OF MORPHOGENETIC PROBLEMS WITHIN THE SHOOT APEX OF OSMUNDA CLAYTONIANA
Authors: KUEHNERT C. C. , Miksche J. P.
Published: January 2018

Excised shoot apices of Osmunda claytoniana were grown under controlled sterile conditions. Histological examination of the normal shoot apex shows that it is comprised of: (1) a promeristem, which possesses 1 or more apical initiating cells at its center; (2) a prestelar tissue consisting of an incipient vascular tissue which flanks the pith‐mother‐cell zone; the pith‐mother‐cell zone gives rise to the pith rib meristem and subsequently to the fundamental parenchyma of the pith; (3) the fundamental parenchyma of the cortex and the fundamental parenchyma of the dermal system both arising from flank cells of the promeristem. Apical initial cells of meristems irradiated with a 127,000 rad acute exposure of a deuteron beam having a diameter of 25μ, histologically examined at 7‐day intervals for a 12‐week period, as early as 3 weeks’ postirradiation, showed the apical initiating cell(s) together with certain of the cells of the pith‐mother‐cell zone to be destroyed. A wound response develops peripherally to the destroyed initials. In addition, an isolated, organized growth center is observed to develop from normal promeristem cells. Incipient vascular tissue and a new pith‐mother‐cell zone are also observed to develop in association with the new center of growth. Implications of the role of the interrelationships between apical initiating cell(s) and other cells of the meristem and the role they may play in maintenance of meristematic integrity within the shoot meristem are discussed.
THE CYTOCHEMICAL REDUCTION OF NITRO BLUE TETRAZOLIUM AS AN INDEX OF POLLEN VIABILITY
Authors: Hauser Edward J. P. , Morrison John H.
Published: January 2018

A new technique for estimating pollen viability utilizing Nitro Blue Tetrazolium (Nitro‐BT) is given. Pollen of 16 taxa was studied and scored for stainability. A comparison was made between Nitro‐BT‐stained pollen samples and aniline‐blue‐lactophenol‐stained samples, because the validity of the latter stain has been questioned in recent years. It is demonstrated that Nitro‐BT can discriminate between pollens which have a capacity for oxidative metabolism, representing potential viability, and those which do not. Suggestions for pollen stainability studies are given.