bluuebunny/crossref_metadata_2025 huggingface dataset:
GENETICS OF PHYTOPATHOGENIC FUNGI. XV. A GENETIC STUDY OF RESISTANCE TO SODIUM ORTHO‐PHENYLPHENATE AND SODIUM DEHYDROACETATE IN PENICILLIUM EXPANSUM
Authors: Beraha L. , Garber E. D.
Published: January 2018

Six mutants of Penicillium expansum resistant to sodium ortho‐phenylphenate (SOPP) and four mutants resistant to sodium dehydroacetate (DHAS) were characterized with respect to their levels of resistance, cross‐resistance, virulence, and morphology. The SOPP‐resistant mutants were recessive and the DHAS‐resistant mutants, dominant. The mutants resistant to 50 mg/liter SOPP were avirulent; the mutants resistant to 300 mg/liter DHAS were atypically virulent. Three SOPP‐resistant mutants and two DHAS‐resistant mutants were shown to be nonallelic in each case. By means of the parasexual cycle four linkage groups were proposed to account for the segregants from 14 diploids involving 16 markers.
BIOCHEMICAL EFFECTS OF VICTORIN ON OAT TISSUES AND MITOCHONDRIA
Authors: Black Homer S. , Wheeler Harry
Published: January 2018

Victorin, the pathotoxin produced by the plant pathogenic fungus Helminthosporium victoriae, causes changes in respiration and permeability which are typical of diseased plant tissues. To provide information on the site and mode of action of this toxin, the effects of victorin on mitochondria were studied and the nature and quantities of materials released from victorin‐treated tissues were determined. Victorin added to isolated mitochondria had no effect on release of electrolytes or on oxidative‐phosphorylative capacity. Hence the high respiratory rate found in victorin‐treated tissues does not appear to be the result of a direct effect of the toxin on the respiratory centers. With mitochondria extracted from tissue pretreated with victorin, electrolyte release was unaffected but oxygen uptake was slightly higher and phosphate esterification considerably lower than controls. Thus the toxin produces indirect effects on mitochondrial activity, but the relation of these effects to tissue respiration remains undetermined. Victorin‐treated tissue lost much larger quantities of certain organic and inorganic materials than control tissue with the most striking difference in the amount of potassium released.
HISTONES AND ALKALINE FAST GREEN STAINING OF ONION ROOTS
Authors: Gifford Ernest M. , Dengler Ronald E.
Published: January 2018

Onion root tips were freeze killed or fixed in 12 different chemical fixatives to determine the possible effects of such treatments on subsequent staining with alkaline Fast green (pH 8.0‐8.1) to reveal the presence of histones. Ethanol, methanol, neutral formalin, and a mixture of methanolchloroform‐acetic acid produced nearly comparable results. Subsequent to fixation or freeze drying the sections were treated with hot 5% trichloroacetic acid (TCA) to remove nucleic acids prior to Fast green staining. Staining of histones does not occur in chemically fixed material if TCA hydrolysis is omitted. Nuclei, chromosomes during mitosis, and cytoplasm (to varying degrees) were stainable after TCA treatment. Positive staining occurs in nuclei, nucleoli, and cytoplasm in freeze‐dried material with or without prior TCA treatment. Comparisons are made with chemical fixations. The use of ribonuclease instead of TCA permits staining of the cytoplasm and of chromosomes during mitosis. Discussions are included on the stainability of nucleoli and the possibility that native histone is associated with ribonucleic acid (RNA).
MORPHOLOGICAL AND ECOLOGICAL STUDY OF PHYSODERMA DULICHII
Authors: Johns Robert M.
Published: January 2018

A new species of aquatic Phycomycete, Physoderma dulichii Johns, parasitic on the aquatic sedge Dulichium arundinaceum (L.) Britt., is described from northern Michigan. This parasite infects and kills the upper epidermal cells of the host leaves. Macroscopically, infection by P. dulichii is indicated by striking brown bands with irregular margins, at intervals on the upper surfaces of the leaves. Like other species of Physoderma, this organism's development includes two distinct phases, an epibiotic monocentric phase producing asexual zoospores and an endobiotic polycentric phase bearing thick‐walled resting spores that germinate after an extensive period of maturation at low temperature to form zoospores. The morphology and development of the two phases and of resting spore germination are reported in detail. Only the immature leaves of the host are susceptible to infection, which may be initiated by the introduction of mature resting spores, zoospores from germinated resting spores, or zoospores from epibiotic sporangia. Resting‐spore zoospores may also produce the endobiotic stage directly. Initiation of infection in nature requires that the terminal cluster of immature leaves on the host plant be submerged, but infection of subsequently formed leaves of emergent culms can be accomplished through the agency of zoospores from epibiotic sporangia on older leaves. The relation of infected stands of hosts to their environment is discussed and the importance of standing water to infection noted. The geographical distribution of the parasite shows correlation with the drainage basins of the Great Lakes, the St. Lawrence River, and the northern Atlantic Coastal Plain
THE DIFFERENTIATION OF PIGMENTATION IN FLOWER PARTS. I. THE FLAVONOID PIGMENTS OF IMPATIENS BALSAMINA, GENOTYPE IIHHPrPr, AND THEIR DISTRIBUTION WITHIN THE PLANT
Authors: Hagen Charles W.
Published: January 2018

Chromatographic analysis of stems, sepals and petals of inbred Impatiens balsamina of the red‐flowered genotype llHHPrPr has revealed a characteristic assemblage of flavonoid pigments in each organ. The more conspicuous compounds have been identified or partially characterized. The stems possess 3‐monoglucosides of kaempferol, quercetin, pelargonidin, cyanidin and, presumably, delphinidin. The variety of pigments is less in flower parts than in stems, and less in petals than in sepals, but the flower parts exhibit a greater elaboration of substituents on the aromatic nuclei. The paired petals of mature flowers are pigmented by p‐coumaroyl and feruloyl esters of pelargonidin‐3, 5‐diglucoside supplemented by more highly substituted derivatives of pelargonidin and by large amounts of kaempferol as the aglycone and two glucosides. The distribution of pigments has significance in the biology of the plant as well as providing an approach to studies of factors which control flower differentiation.
PARASITISM IN PHOLISMA (LENNOACEAE). I. EXTERNAL MORPHOLOGY OF SUBTERRANEAN ORGANS
Authors: Kuijt Job
Published: January 2018

The external features of the subterranean organs of coastal Californian Pholisma depressum Greene are described. A dimorphic root system exists. Long, stout roots (pilot roots) serve for vegetative propagation in reaching other host roots. Short, unbranching, more slender roots originating from the pilot roots are haustorial in function. Shoots seem to arise only on pilot roots. Host attachment is achieved through the direct transformation of the apical meristem of haustorial roots into the haustorial organ. The basal part of the shoot is also able to produce roots when near host roots, and may form lateral branch shoots either directly or after new haustorial connections are formed. Both types of roots arise endogenously. The invaded host root undergoes considerable hypertrophy. The intrusive organ itself forms a massive but irregular body. More than one haustorial root may enter even a small host root. Self parasitism may occur but is not common.
STUDIES ON THE SOLUBLE CARBOHYDRATES AND CARBOHYDRATE PRECURSORS IN GERMINATING SOYBEAN SEED
Authors: Abrahamsen Mary , Sudia T. W.
Published: January 2018

The total soluble carbohydrate fraction of the cotyledons and embryo axis of germinating soybean seedlings declined rapidly during the first 3 days of germination. This depletion began earlier in the embryo axis than in the cotyledon. The total carbohydrate content of the cotyledons of plants grown in light and plants grown in dark was approximately the same for the first 7 days of germination. Between day 9 and 13 the total carbohydrate content of the cotyledons of soybean seedlings grown in dark was higher than that of plants grown in light. The reducing sugar content of light‐grown soybean cotyledons increased approximately 5‐fold during the first 9 days of germination, whereas that of dark‐grown soybean cotyledons increased more slowly during this interval. Reducing sugars in the embryo increased during the early stages of germination until they approximately equalled the total carbohydrate. Between day 4 and 13, oil was depleted more rapidly in the cotyledons of seedlings grown in light than those grown in the dark. The reserve carbohydrates of soybean embryos and cotyledons consisted primarily of low molecular weight oligosaccharides, particularly sucrose, stachyose, and raffinose. These compounds decreased rapidly during germination. The isocitritase activity in the cotyledons of germinating soybean seeds increased rapidly for the first 6 days of germination and then decreased for the next 7 days. The isocitritase activity of plants grown in the dark was higher than that of the plants grown in light at all stages of development, particularly between day 7 and 11.
THE FLESHY, CYLINDRICAL, SUBTERRANEAN GAMETOPHYTE OF SCHIZAEA MELANESICA
Authors: Bierhorst David W.
Published: January 2018

The gametophytes of Schizaea melanesica from Fiji are described. The unbranched body has a near‐basal, tuberous portion and a more distal thinner portion. The basal portion becomes tuberous as the result of a peripheral thickening meristem. The apex of the gametophyte has an apical cell with three cutting faces. Scattered over the surface are rhizoid‐like outgrowths which seem to be the homologs of the hairs and not the rhizoids in other schizaeaceous genera. Antheridia are likewise scattered and are particularly similar to those of other members of the family. No archegonia were seen. Superficial buds are produced. The internal tissues are entirely parenchymatous and contain fungal hyphae. Phylogenetic and morphological implications are discussed.
CULTURALLY INDUCED VARIATION IN FOUR MORPHOLOGICALLY DIVERSE BLUEGREEN ALGAE
Authors: Pearson Joyce E. , Kingsbury John M.
Published: January 2018

Characters used in taxonomic placement at levels from family to species appeared, disappeared, or varied widely, while others remained constant, in cultures of four disparate species of blue‐green algae (Cyanophyta) under varying conditions of culture. Species of Anabaena and Gloeocapsa displayed fairly stable characteristics. Species of Calothrix and Lyngbya exhibited much greater variability, especially in twisting of filaments, presence or absence of constrictions at the cross walls, abundance of heterocysts, pseudovacuoles, fragmentation of filaments, and change of color. Color change was associated with abrupt pH shift in Lyngbya and could be reversed by adding nitrate. In the putatively nitrogen‐fixing Anabaena, similar change in color with age was not associated with sharp pH shift, nor could it be reversed with nitrate. In general, growth on agar in turbulent conditions and with decreased CO2–O2 exchange was less than that obtainable under other conditions, and media with acid pH were partially or totally inhibitory to growth.
SEASONAL VARIATIONS IN THE PROPORTIONS OF SUBERIZED AND UNSUBERIZED ROOTS OF TREES IN RELATION TO THE ABSORPTION OF WATER
Authors: Kramer Paul J. , Bullock Henry C.
Published: January 2018

Growing root tips usually constituted less than 1 per cent and mycorrhizal roots less than 6 per cent of the total root surface under a 34‐year‐old pine stand. Growing root tips usually constituted less than 1 per cent of the total root surface under a yellow poplar stand, although one sample taken in May contained 9 per cent of unsuberized roots. The water permeability of various types of roots was measured under a pressure gradient of 31 cm of mercury. It differed widely among individual roots, ranging from an average of 6.6. mm3/cm2/hr for suberized pine roots 1.33 mm in diameter, to 36.6 mm3 for suberized pine roots 3 mm in diameter, and 178 mm3/ cm2/hr for unsuberized roots grown in water culture. Water intake through a group of unsuberized roots grown in soil averaged 37.4 mm3/cm2/hr. The permeability of yellow poplar roots varied even more, ranging from essentially zero to 30,000 mm3/cm2/hr. It is concluded that the major part of water absorption in pine occurs through suberized roots, some through mycorrhizal roots, and relatively little through growing root tips. Likewise, in yellow‐poplar most of the water probably enters through suberized roots. Further study is needed of the role of suberized roots in water and salt absorption.
EFFECT OF ATRAZINE ON CHLORELLA VULGARIS
Authors: Ashton F. M. , Bisalputra T. , Risley E. B.
Published: January 2018

Samples of a synchronous culture of Chlorella vulgaris were treated with: (a) atrazine, (b) atrazine + glucose, or (c) glucose. Cultures were sampled 0, 24, 48, and 72 hr, after treatment. Chlorophyll and packed cell volume were determined on each, and electron micrographs were taken. Atrazine prevented normal increase in packed cell volume and chlorophyll; this cessation of growth was counteracted by glucose. Chlorella utilized both the endogenous products of photosynthesis and an exogenous energy source, glucose in this instance, simultaneously. The atrazine‐treated cells did not contain starch; control cells, atrazine‐glucose‐ and glucose‐treated cells did. Atrazine did not cause any observable abnormalities in cell organelles.
ONTOGENY OF ALEURONE GRAINS IN COTTON EMBRYO
Authors: Engleman E. Mark
Published: January 2018

Cotyledon mcsophyll cells in maturing seeds of Gossypium hirsutum from aleurone grains by accumulation of protein and other materials in vacuoles. Globoids and unidentified, electron‐dense particles can be found in the matrix of amorphous protein. As revealed by electron microscopy, the vacuoles appear to communicate with cisternae of endoplasmic reticulum in early stages of development. This paper and many reports in the literature cast doubt on the reported plastid nature of certain aleurone grains.
STRUCTURE AND DEVELOPMENT OF HERPOMYCES STYLOPYGAE (LABOULBENIALES)
Authors: Tavares Isabelle I.
Published: January 2018

Herpomyces stylopygae Speg., parasitic on Blatta orientalis L., may be readily distinguished from H. periplanetae by the narrow shield with a black base and by the slender perithecium with narrow basal neck cells. Thalli with fully formed shields typically grow attached to minute setae. The female primary axis varies in form according to its position with relation to the host cuticle. Extensions arising from its two intermediate cells, or their derivatives, produce perithecial upgrowths; the basal cell of each upgrowth develops into the secondary receptacle or shield; the apical cell undergoes two transverse divisions and three vertical divisions to form the first basal cells of the perithecium and the first tier of outer wall cells. As transverse divisions of the wall cells occur, one first‐tier cell grows inward to form a series of carpogonial upgrowths, while four inner wall cell rows arise from third‐tier cells and an extra fourth‐tier cell. The male produces antheridial branches from the three upper cells.
ASCOCARPIC CENTRUM ONTOGENY OF SPECIES OF HYPODERMATACEAE OF CONIFERS
Authors: Gordon C. C.
Published: January 2018

Studies on the morphology of the ascocarps of 39 species of Hypodermataceae revealed several previously unknown cytological features. Two basic and one intermediate type of centrum ontogeny are discussed. Ascal initiation within Type I centrum occurs in the basal cells of the pseudoparaphyses and involves anastomoses, while ascal initiation within Type II occurs in cells of a plectenchymatous centrum, with no visible anastomosing in the ascocarp. There is frequent anastomosing between vegetative hyphae well in advance of initiation of the ascocarp. Ascal initiation in the intermediate type has ontogenetic sequences similar to those in Types I and II.
THE COMPARATIVE MORPHOLOGY OF THE CANELLACEAE. IV. FLORAL MORPHOLOGY AND CONCLUSIONS
Authors: Wilson Thomas K.
Published: January 2018

The morphology and anatomy of 105 flowers representing 13 species and 6 genera of the Canellaceae are summarized. The flowers are borne in axillary or terminal racemes, cymes, or small groups, or solitary, in an axillary or terminal position. The flowers are characterized as follows: bisexual, hypogynous; sepals 3, thick and leathery; petals, 5–12, free or united into tube at base, rather thick, in 1 or 2 whorls and/or spirals; androecium of 6–12 stamens united by their filaments forming a tube, anthers with longitudinal extrorse dehiscence; gynoecium of 2–6 carpels fused by their ventral margins; 2–6 placentae. There are 2 vascular bundles (rarely 3) to each sepal, 3 to each petal (some of the inner petals have only 1), 1 to each stamen and 1 trace to each carpel. The petal and stamen bundles have a common origin. All the data accumulated in this series on the Canellaceae indicate that the correct systematic placement of the Canellaceae is in the woody Ranales, perhaps in a complex with the Myristicaceae.
QUANTITATIVE STUDY OF DEVELOPMENT OF THE GIANT COENOCYTE, CAULERPA PROLIFERA
Authors: Chen James C. W. , Jacobs W. P.
Published: January 2018

The lengths of rhizomes, rhizoid clusters, and leaves of many plants of Caulerpa prolifera cultured under controlled conditions were measured daily. Their rates and patterns of growth were analyzed mathematically with the aid of an electronic computer. All organs elongated at the rate of ca. 4.4 mm per day. Rhizomes elongated linearly for more than 2 weeks, and curvilinear regression usually did not improve the fit significantly. Rhizome elongation is apical. Every 1.18 days, on the average, a rhizoid cluster developed on the lower surface of each rhizome. The length of the younger rhizoid clusters shows a linear relationship to their distance from the rhizome tip. Little or no significant improvement of fit resulted from fitting polynomials of the 2nd through 4th degree. Accordingly, by extrapolating the straight line to zero rhizoid length, we calculated the presumptive site of rhizoid initiation to be 0.84 mm from the rhizome tip. The rate and distribution of growth were compared to those of other coenocytes and of multicellular plants.
THE ROLE OF ALLELOPATHIC SUBSTANCES IN THE “SMOTHER CROP” BARLEY
Authors: Overland Lillian
Published: January 2018

The high degree of success of barley as a “smother crop” generally has been attributed to physical competition for nutrients and water. However, it was found that even in the absence of such competition, barley still inhibits germination and growth. This occurred both in mixed cultures receiving adequate nutrients and water and in germination tests. Aqueous leachates of seeds and roots of barley caused similar inhibition of germination and growth, thereby indicating an inhibitory allelopathic substance. A specificity of reaction was found, with the greatest inhibition occurring with Stellaria media (L.) Cyr., less with Capsella bursa‐pastoris (L.) Medic. and tobacco (Nicotiana tabacum L.), and no significant effect with wheat (Triticum aestivum L.). A concentration effect and possible periodic production of the inhibitor were indicated. Living plants and aqueous leachates of living roots were more inhibitory than dead ones, thereby supporting the hypothesis of an active metabolic secretion of the allelopathic substance. Preliminary attempts to identify the active inhibitory components demonstrated the presence of alkaloids, with a much greater concentration of substance in the living than in the dead root leachates. The alkaloid, gramine, known to occur in barley, was found to have an inhibitory effect on the growth of Stellaria media and it is suspected as an active component of the root leachates. These results suggest that factors other than the previously assumed physical competition are involved in the mechanism of the “smother crop” barley.
ORGANOGENESIS IN THE CARPELLATE FLOWER OF DRIMYS LANCEOLATA
Authors: Tucker Shirley C. , Gifford E. M.
Published: January 2018

This study of floral development in Drimys lanceolata in Section Tasmannia provides a basis for comparison with D. winteri, a member of the section Wintera, which has been described previously. The carpellate flowers of D. lanceolata have 2 sepals, 4–6 petals, and a solitary carpel, which form in acropetal succession. In symmetry the flower and its apical meristem are bilateral rather than radial, as in the flower of Drimys winteri. The floral apex of D. lanceolata is zonate while that of D. winteri is organized as a mantle and core. Preceding carpel initiation the floral apex of D. lanceolata is narrowly wedge‐shaped, while that of D. winteri is low‐convex. The entire apex is utilized in carpel initiation in D. lanceolata, involving many subsurface cell divisions over the entire summit. No apical residuum remains, and the carpel is terminal. In this feature the contrast with D. winteri is particularly marked, since in the latter, carpels are initiated laterally around the floral apex, which c an be recognized as an apical residuum after all appendages have formed.
AN ANALYSIS OF STAMEN FILAMENT GROWTH OF NIGELLA HISPANICA
Authors: Greyson Richard I. , Tepfer Sanford S.
Published: January 2018

The post‐meiotic stamen filament of Nigella hispanica L. under greenhouse conditions grows in length from 1 mm to approximately 10 mm at maturity in 16 days. Analysis of the filament epidermis suggests that the intercalary meristem is diffuse along the filament with a mid‐point of activity near the center of the filament. The point of maximal activity, while initially central, is variable as cell division nears completion. Measurement of cell lengths along filaments suggests that an elongation gradient from base to tip is operative in filaments 1 mm and longer. Average cell lengths of epidermal cells increase faster than do those of terminal cells. Once average cell length begins to increase in any region of the epidermis it continues to do so until flower maturity. At maturity the longest epidermal cells are near the filament base and the shortest cells are at the tip. The differences between cell division and cell elongation patterns suggest that these two processes are controlled by different sites or substances. A comparison is made between the development of the Nigella filament and other determinate organs having intercalary meristems.
COMPARATIVE ANATOMY OF ENDOGENOUS BUD AND LATERAL ROOT FORMATION IN CONVOLVULUS ARVENSIS ROOTS CULTURED IN VITRO
Authors: Bonnett Howard T. , Torrey John G.
Published: January 2018

The anatomy of endogenous bud and lateral root formation was studied in Convolvulus arvensis roots cultured in vitro. Although early stages in the initiation of buds and roots were found to be identical, continued development of primordia into roots or buds was accompanied by differences in participating primary root tissues, in rates of development, and in orientation of cell divisions. Evidence for the existence of a primordium capable of developing into either a bud or root is discussed with reference to Convolvulus roots and other plant parts shown to have similar morphogenetic potentials.
ONTOGENY AND STRUCTURE OF THE FLOWER AND FRUIT OF PERESKIA ACULEATA
Authors: Boke Norman H.
Published: January 2018

Flowers ofP. aculeataare perigynous. The receptacle cup bears a series of lanceolate bracts, which become reflexed in the fruit, and its rim bears a series of small, triangular bracts, which are sharply delimited from the perianth segments. Vascular anatomy indicates that there is a short floral tube formed by the adnation and connation of the bases of the stamens and perianth segments. The inner side of this floral tube forms an extensive cylindrical nectary; the outer side is adnate to the receptacle. There are usually five carpels, each bearing a single ovule. Carpel tips are free, but their bases are congenitally connate. During ontogeny, the adaxial faces of the carpels grow together, forming a solid style. The base of the ovary is partially divided into locules by small partitions, which represent the fused margins of connate carpels. The tip of the floral receptacle (residual meristem) becomes a convex body which enlarges in the fruit, filling that portion of the ovary cavity not occupied by seeds. The superior ovary and the columella formed in the fruit are probably primitive characteristics, but in all other respects the flower ofP. aculeataappears to be advanced. It is a product of evolutionary reduction.
DEVELOPMENT OF THE SEED AND FRUIT IN RHINANTHUS MAJOR AND R. SEROTINUS
Authors: Tiagi B.
Published: January 2018

There are seven sessile, campylotropous, discoid ovules in each loculus of the anteroposteriorly flattened bilocular ovary. They are arranged alternately in two rows in each chamber on the axile placenta which is nodular where the ovules are borne. Nucellus degenerates early except at the chalazal end of the curved embryo sac, and the inntermost layer of the integument functions as endothelium. The aggressive, multinucleate micropylar haustorium grows as a tubular body through the micropylar canal and ramifies in the placenta while the two‐nucleate chalazal haustorium creates a large space by digesting a good deal of the chalazal tissue. Endosperm is differentiated into three regions: the middle storage, the haustorial micropylar, and the chalazal. Thickness of the integument is considerably added to by the endothelium and by its surrounding meristematic zone of the integument. There are two prominent wings on the dorsal and smaller ones on the lateral faces of the cochlidiospermous seed, its ventral face being occupied by a prominent basal body. A heavily cutinized envelope, formed by the endothelium, surrounds the ovoid storage endosperm. Testa of the seed is mainly composed of the thickened epidermis and the endothelium. The micropylar and the chalazal parts of the endosperm become tanniferous and serve to plug the two ends of the seed. Embryo is straight, and it bears two cotyledons and two plumular leaves.
A REINTERPRETATION OF THE ONTOGENY OF THE ASCOCARP OF SPECIES OF THE ERYSIPHACEAE
Authors: Gordon C. C.
Published: January 2018

A study of four species of Erysiphaceae (Uncinula salicis, Podosphaera leucotricha, Erysiphe cichoracearum, and Microsphaera diffusa) revealed that the binucleate stages of the ascocarp are initiated in a similar manner to those of Diporotheca rhizophila Gordon & Shaw. The “appendages” developing on immature ascocarps are considered to be receptive hyphae. Appendages characteristic of mature ascocarps are produced much later. Lysis of certain centrum cells occurs, and asci are initiated from some of the remaining binucleate centrum cells. Resorption of centrum cells by the asci is supported by this investigation, corroborating Björling's earlier studies on Erysiphe graminis.
STUDIES ON STRIGA SENEGALENSIS III. IN VITRO CULTURE OF SEEDLINGS. ESTABLISHMENT OF CULTURES
Authors: Okonkwo S. N. C.
Published: January 2018

Striga senegalensis seeds were cultured on Knop's and modified Murashige‐Skoog's medium. An aqueous root exudate/extract of the host (Sorghum vulgare) was found essential for the germination of seeds in vitro. The seedlings grew better on a medium containing sucrose than on mineral salts alone. Only limited growth was achieved on Knop's medium. Better growth was supported by Murashige‐Skoog's medium. By transfer to larger culture vessels seedlings were kept in the latter for several months. The seedlings developed chlorophyllous shoots in light and flowered after 4–4½ months. The successful culture of these seedlings in a simple medium of only mineral salts and sugar indicates that the parasitic seedling depends on the host for only water, mineral salts and sugar and not for more elaborate substances.
STUDIES ON STRIGA SENEGALENSIS IV. IN VITRO CULTURE OF SEEDLINGS. EFFECT OF VARIOUS SUGARS AND GLUTAMINE
Authors: Okonkwo S. N. C.
Published: January 2018

In Murashige and Skoog's medium it has been shown that except for sucrose, other sugars including mono‐, di‐, and tri‐saccharides can be utilized as carbon sources by Striga seedlings. These include glucose, fructose, mannose, galactose, lactose, xylose, maltose and raffinose. The best seedling growth was recorded at 0.06 m concentration for most of these sugars. Ribose, sorbose, rhamnose, and mannitol were not utilizable carbon sources. Glutamine proved to be an excellent nitrogen source for the seedlings. It satisfied the nitrogen requirements at 400 mg/liter in the absence of inorganic nitrogen in the medium. In the presence of inorganic nitrogen, it supported growth over and above that accountable for by inorganic nitrogen alone.
JENSENIA MACROGYNA, A NEW PHILIPPINE HEPATIC
Authors: Miller Harvey A. , Inoue Hiroshi
Published: January 2018

Jensenia macrogyna, sp. n. from Mt. Pulog, Luzon, differs from J. decipiens (Mitt.) Grolle in being smaller and having longer marginal teeth, a longer involucre, and smaller cells in the wing and upper epidermis. Male plants have a plane frond and a long stipe; females, a clasping frond and short stipe.
ORGANIZATION OF THE ADVENTITIOUS ROOT APEX IN TAMARIX APHYLLA
Authors: Ginzburg Chen
Published: January 2018

Adventitious roots on branches of Tamarix aphylla (L.) Karst. develop in hyperhydric outgrowths of the lenticels. The following stages could be distinguished in the formation of the apices of these roots: (1) initiation, (2) a stage of random divisions, (3) a stage of transverse divisions, with respect to the longitudinal axis of the primordium, (4) formation of the procolumella, (5) differentiation of the procambium, the cortical meristem and the protoderm, (6) enlargement of the promeristem, and (7) emergence.
A SYNOPSIS OF THE GENERA AND SPECIES OF THE TRIBE THELEBOLEAE (= PSEUDOASCOBOLEAE)
Authors: Kimbrough James W. , Korf Richard P.
Published: January 2018

Examination of genera of the Pseudoascoboleae (Ascomycetes, Discomycetes, Ascobolaceae) revealed that many were polytypic. Characters presently used to distinguish these genera are considered to be artificial and true relationships cut across accepted generic lines. Of the genera treated, Thecotheus and parts of Ascophanus, since their asci blue in iodine and their spores bear callose‐pectic markings, are considered more closely related to the Pezizeae. Other genera are excluded from the Pseudoascoboleae because of other striking characters. Since the Pseudoascoboleae is shown to be an artificial grouping, it is proposed to abandon the name, using instead the tribe name Theleboleae, placed in the Pezizaceae rather than the Ascobolaceae, for all of those genera with asci that do not blue in iodine, with smooth, elliptical spores without oil guttules, and with eight‐spored and multispored species. Four new genera are described: Iodophanus, for species of Ascophanus with iodine‐positive asci; Coprotus, for segments of Ascophanus and Ryparobius; Caccobius, for species intermediate to Ascozonus and Thelebolus; and Trichobolus, for the setose members of Thelebolus. The species of Ryparobius not belonging to Coprotus are transferred to Thelebolus.
THE EXPERIMENTAL FORMATION OF POLYPLOIDY AND ITS EFFECT IN THE GENUS MUSA
Authors: Vakili Nader G.
Published: January 2018

Polyploidy was induced in two Musa species and their hybrid by means of immersing newly germinated diploid seedlings in 0.5% aq. colchicine solution. Tetraploid M. balbisiana plants were taller and more robust but had slower growth rate, droopier leaves, fewer suckers, and scantier root systems than the diploids. Tetraploidy affected fruit size and shape in M. balbisiana and in M. acuminata. Tetraploidy did not affect bunch size (the number of fruit‐bearing nodes) in M. acuminata banksii but caused great reduction in bunch size of M. acuminata microcarpa ‘Zebrina.’ Doubling of the chromosome number resulted in doubling of the anthocyanin concentration in the leaves of the pigmented banana plants. Colchicine‐induced female sterility was detected in a treated diploid plant of M. acuminata subsp. microcarpa. A number of either female or male, or both female and male sterile plants were encountered in colchicine‐induced tetraploid M. acuminata species. Only one secondary M. balbisiana tetraploid plant was found to be partially female sterile. Colchicine treatment of the seedlings resulted in chromosomal irregularities at mitosis. Chromosomes appeared as open chains, rings and multiple configurations at metaphase. In the majority of cases doubled chromsomal complements reverted to their original number. However, there were cases in which diploids were induced to tetraploidy and later reverted to triploidy instead of diploidy. Also, there were cases in which triploids were doubled to hexaploidy and later reverted to tetraploidy instead of triploidy. From the close morphological similarity between a number of triploid and tetraploid M. balbisiana plants and some edible triploid cultigens belonging to the “ABB Group,” it is suggested that the karyotype of some of these cultigens could be “BBB” rather than “ABB” which contains one “A” M. acuminata genome. New pathways and additional evolutionary possibilities are incorporated into Simmonds’ scheme on the evolution of edible bananas.
HETEROKARYON FORMATION AND GENETIC ANALYSES OF COLOR MUTANTS IN ASPERGILLUS HETEROTHALLICUS
Authors: Kwon Kyung‐Joo , Raper Kenneth B.
Published: January 2018

Heterokaryon compatibility between strains of Aspergillus heterothallicus was tested by using prototrophic mutants of contrasting conidial head colors obtained by ultraviolet radiation. Heterokaryons were formed between mutants only when two conditions were fulfilled: The mutants had to be of the same mating type, and the isolates from which the mutants were derived had to be of similar macroscopic growth characteristics and mycelial pigmentation. Heterokaryotic heads were conspicuously striate, being composed of spore chains pigmented as the parental types, and representing, in most cases, examples of an “autonomous” nuclear action. Heterokaryotic heads of unusual interest, resulting from “autonomous‐nonautonomous” type of gene actions, were produced in combinations of a pinkish tan (PT) mutant. The nuclear action of the PT mutant was nonautonomous regardless of the type of mutant with which it was paired, whereas the nuclear action of the other head‐color mutants was autonomous. Genetic analyses of head‐color mutants were conducted by using all possible crosses between mutants derived from strains WB 4982 (A mating type) and WB 5086 (a mating type). It was found that similar color mutations of these two strains were allelic. All mutations responsible for different head colors, however, were found to be nonallelic to each other. The interactions between the different head‐color mutants were studied in double mutants formed in the aforementioned crosses. Epistatic‐hypostatic relationships between the different mutations were determined, and such relationships were used in the construction of a possible biosynthetic sequence leading to the production of the wild‐type (green) pigment of conidial heads. The main sequential steps for the biosynthesis of conidial pigmentation appear to proceed from white to yellow, to brown, to brownish green, and to green.
SYNTHETIC HYBRIDS OF NEW WORLD AND OLD WORLD AGROPYRONS: III. AGROPYRON REPENS × TETRAPLOID AGROPYRON SPICATUM
Authors: Dewey Douglas R.
Published: January 2018

Three hybrids of A. repens, 2n = 42, × A. spicatum, 2n = 28, and two reciprocal hybrids were obtained from emasculated and unemasculated crosses, respectively. The 35‐chromosome hybrids tended to be morphologically intermediate between the parent species but resembled A. repens more closely than A. spicatum. A. repens behaved cytologically as a segmental autoallohexaploid, and A. spicatum acted cytologically as an autotetraploid. Mean chromosome associations of 8.04 I, 12.72 II, 0.41 III, 0.06 IV, and 0.009 V were observed in 116 hybrid cells at metaphase I. Most chromosome pairing in the hybrids was attributed to autosyndesis. A. spicatum, A. repens, and their hybrids were represented by genome formulas of SSSS, R1R1X1X1X2X2, and SSR1X1X2, respectively. Hybrid fertility ranged from 0.02 to 0.69 seeds per spikelet.
RHIZOID CELL DIFFERENTIATION IN THE FERN GAMETOPHYTE OF PTERIS VITTATA
Authors: Crotty William J.
Published: January 2018

A series of events in the differentiation of rhizoid cells in the gametophyte of Pteris vittata L. is described. Differential in vivo staining reactions make it possible to trace a sequence of stages from pre‐mitotic nucleocytoplasmic staining (corona stage), through the events of mitosis, to formation of an internally segmented rhizoid cell which then grows out from the parent thallus cell. When the standard ribonuclease test is employed, basophilic protoplasmic staining due to pyronin is prevented in developmental stages up through early formation of the rhizoid cell. Staining in these stages is therefore assumed to be due to ribonucleic acid associated with protein synthesis. A new developmental phase starts just prior to the protrusion growth of this cell when an intensely pyroninophilic material appears at the membrane of the rhizoid cell nucleus and along cytoplasmic strands radiating to the peripheral regions of the cell. The staining of this newly synthesized material cannot be prevented by ribonuclease treatment, and it shows strong positive tests for protein and polysaccharide. As long as the rhizoid continues to grow, this material remains concentrated in the growing tip region. Material showing similar staining reactions is also found in the cells of the meristematic notch area. Although thallus cell walls do not stain, the rhizoid cell wall adsorbs basic stain, in some cases, metachromatically. Finally, it is suggested on the basis of observations reported here that the sometimes neglected role of the nucleus in theories of unequal cell division‐differentiation should be re‐examined.
THE PATHOLOGY OF HYPODERMELLA LARICIS ON LARCH, LARIX OCCIDENTALS
Authors: Cohen Leon I.
Published: January 2018

A study of the larch needle disease caused by Hypodermella laricis provided information on the mode of infection, the manner of spread, and the relationship between the parasite and its host, Larix occidentalis. Infection by spores occurs in early spring as soon as the leaves emerge, but there is no evidence that hyphae invade the dwarf shoots. The fungus disrupts the normal abscission mechanism, and the fructifications and spores of H. laricis develop on the leaves which remain attached to the dwarf shoots. The time of precipitation is a decisive factor in the initiation of the disease, i.e., infection occurs only when precipitation coincides with the emergence of young leaves. However, vulnerability to infection diminishes rapidly as the leaves mature. By observing leaf size and noting the time of rainfall, the severity of infection can be accurately predicted. Several adaptive mechanisms related to successful parasitism in H. laricis are discussed.
THE ROLE OF AUXINS AND CYTOKININS IN THE RELEASE OF BUDS FROM DOMINANCE
Authors: Sachs Tsvi , Thimann Kenneth V.
Published: January 2018

The paper deals with the general problem of the physiological basis of branching, and the roles of known and unexplored factors in sensitivity to apical dominance. It is shown that when pea seedling shoots are completely or partially inhibited by other shoots on the same plant auxin can promote their elongation, even though it does not have this effect on inhibited buds. This influence of auxin is only exerted on internodal elongation and not on apical growth. When kinetin in a solution of alcohol and carbowax is applied directly to the lateral buds of pea seedlings, it releases them from inhibition by the growing apex. It is shown that the role of alcohol in this solution is to act as a surfactant, permitting good contact with the buds, while that of carbowax, being hygroscopic, is to maintain a thin film of solution over the buds. Buds thus released from apical dominance by kinetin do not elongate as much as do uninhibited control buds. Such kinetin‐treated buds can, however, be made to elongate normally by the application of auxin locally to their apices. It is concluded that growing shoots are relatively insensitive to correlative inhibition because they synthesize two types of growth substances, namely, auxin, which antagonizes the inhibitory effect on internodal elongation, and cytokinins, which permit the apex itself to develop. In the discussion it is brought out that many cases of branching, which appear at first to bear little relation to one another, can be understood on the basis of two principles, namely: (1) Any reduction in the growth rate of a dominant apex reduces its inhibitory effect on other apices, and (2) once an apex starts growing it becomes less sensitive to inhibition by other apices These generalizations and the experimental results are tentatively interpreted in terms of an interaction between the syntheses of auxin and of cytoldnin.
THE CAMBIUM AND SEASONAL DEVELOPMENT OF THE PHLOEM IN ROBINIA PSEUDOACACIA
Authors: Derr William F. , Evert Ray F.
Published: January 2018

The cambium in black locust consists of several layers of cells at all times. Cambial reactivation (division) is preceded by a decrease in density of cambial cell protoplasts and cell wall thickening but not by cell enlargement. During the resumption of cambial activity, periclinal divisions occur throughout the cambial zone. Early divisions contribute largely to the phloem side. The period of greatest cambial activity coincides with early wood formation. Judged by numerous collections made during two seasons (October, 1960‐October, 1962) the seasonal cycle of phloem development is as follows. Phloem differentiation begins in early April, ends in late September. The amount of phloem produced is quite variable (range: 1‐10 bands of sieve elements per year). Cessation of function begins with the accumulation of definitive callose in the first‐formed sieve elements and spreads to those more recently formed. By late November all but the last‐formed sieve elements are collapsed. All sieve elements are collapsed by mid‐winter and before the resumption of new phloem production in spring. Phloem differentiation precedes xylem differentiation by at least 1 week, and apparently functional sieve elements are present 3 weeks before new functional vessel elements. Xylem and phloem production ends simultaneously in most trees.
BEHAVIOR OF NUCLEOLI AND CONTRACTING NUCLEOLAR VACUOLES IN TOBACCO CELLS GROWING IN MICROCULTURE
Authors: Johnson J. Morris , Jones Leo E.
Published: January 2018

The ability to observe for extended periods of time individual tobacco cells growing in microculture has made it possible to describe the behavior of their nucleoli and contracting nucleolar vacuoles. Nucleoli typically disappeared in prophase and reappeared in telophase. If several nucleoli were present in telophase they generally fused to form only one or two during interphase. In one instance a nucleolus was seen to separate into two nucleoli prior to disappearance in late prophase. In aging and senescent cells the number of nucleoli or bodies similar to normal nucleoli often increased, and occasionally fragmentation of nucleoli was noted prior to death of cells. Budding of solid material from the nucleolus was also observed. The amount of nucleolar material decreased rapidly prior to death of tobacco cells. Nucleolar vacuoles were found to be a general and consistent component of tobacco cells in microculture. Nucleolar vacuoles typically formed and contracted repeatedly in interphase nuclei and apparently released a fluid material into the nucleus. Associated with the contraction of the nucleolar vacuoles was a corresponding decrease in diameter of the nucleolus. Nucleolar vacuoles were observed to occur in about 70% of the actively growing cells examined, whereas they were present in only 33% of the senescent or weakened cells. These data indicate a relationship between nucleolar vacuoles and the morphogenic status of the cells. Since it has been shown by others that the nucleolus is an active site of RNA metabolism, it is suggested that the contracting nucleolar vacuoles may be involved in the controlled release of a soluble product associated with RNA metabolism.
CHROMOSOME NUMBERS IN COMPOSITAE. VI. SENECIONEAE. II
Authors: Ornduff Robert , Mosquin Theodore , Kyhos Donald W. , Raven Peter H.
Published: January 2018

Chromosome counts are reported for 76 taxa and 2 natural hybrids of tribe Senecioneae (Compositae). First counts are reported for several species of Senecioneae as well as for the genera Cadiscus and Whitneya. New chromosome numbers are added to those previously known in Arnica, Cacalia, and Senecio. Additional counts from Arnica support our previous suggestion that x = 19 for this genus. It is assumed that observed meiotic irregularities are associated with apomixis in this genus. Basic chromosome numbers for various New World sections of Senecio are proposed, and certain problems of sectional relationships in this genus are discussed. Chromosome numbers and plant morphology of Cadiscus, Hulsea, and Whitneya indicate that these genera should be removed from Helenieae to Senecioneae. The possible affinity of the anomalous genus Adenocaulon with Mutisieae is discussed. Data presented in the paper further support our earlier proposal that the basic chromosome number for Senecioneae is x = 10.
ORIGIN OF FRAGARIA POLYPLOIDS. I. CYTOLOGICAL ANALYSIS
Authors: Senanayake Y. D. A. , Bringhurst R. S.
Published: January 2018

The genomic relationships between modern Fragaria diploids (European and American F. vesca and F. viridis—2n = 14) and octoploids (F. virginiana and F. chiloensis—2n = 56) were investigated. This contrasts with previous studies where cultivars have represented the octoploids. Critical information on genomic pairing was obtained by comparing chromosome behavior of pentaploid hybrids with that of hexaploid hybrids (obtained by using a recent colchiploid of European F. vesca). Supporting data were also used from an F. chiloensis × Potentilla glandulosa hybrid (2n = 35). A revision of the AABBBBCC (Federova) genomic formula for the octoploids to AAA'A'BBBB is proposed based upon cytological evidence of homology between the AA and “CC” genomes. The phylogeny of the octoploids is postulated.
TRABECULAE IN THE GRAPEVINE INFECTED WITH LEAFROLL VIRUS
Authors: Hoefert Lynn L. , Gifford Ernest M.
Published: January 2018

Microscopic examination of leaf midvein, petiole, and stem sections of Vitis vinifera L. ‘Zinfandel’ infected with the leafroll virus has shown the presence of trabeculae (cellulosic bars or rods which traverse the lumina of cells). The cellulosic nature of these structures has been verified by the use of histochemical tests. Trabeculae were found in interfascicular parenchyma and in phloem parenchyma cells, often in association with oxalate crystals. Trabeculae were not present in healthy grapevines. Other workers have found trabeculae in plants infected by fanleaf virus and tobacco mosaic virus. Arguments are presented for the hypothesis that viruses are responsible for the occurrence of trabeculae in such plants.
PHYSIOLOGICAL CONTROL OF THE DIMORPHIC LEAVES OF CYAMOPSIS TETRAGONOLOBA
Authors: Sparks Phillip D. , Postlethwait S. N.
Published: January 2018

Cyamopsis tetragonoloba, commonly called guar, produces two leaf forms: a simple leaf and a trifoliate leaf. During ontogeny, the simple leaf is always produced prior to the appearance of any trifoliate forms. The number of simple leaves initiated during the early phase of ontogeny is partially controlled by environmental conditions. Both short daylengths and high temperatures delay the production of the trifoliate form. Treatments using gibberellic acid and reduced light intensity favor production of simple leaves. Removing the cotyledons of young seedlings also favors the simple leaf form. Some consider a change in leaf form as an indication of a change from the juvenile phase to the adult phase of growth. However, in guar when the capability to reproduce is used as the basis for the determination of phase change, a change in leaf form is a separate phenomenon.