摘要:

The seasonal study of the vegetative shoot apex and its direct derivatives in the dicotyledonous angiospermMyriophyllum heterophyllumduring the production of its 3 leaf types revealed a great similarity in the anatomy of the apex which produced them. The apex consisted of 2 tunica layers and a corpus that varied slightly. The corpus consisted of the corpus initials, the central rib meristem, and the inner layers of the flanking meristem. The work was compared with several works, but in particular with that of Vochting (1872). Vochting worked with another species,M. spicatum,using the terminology of the histogen concept. This work has verified many of Vochting's observations in the light of today's terminology and extends the range of seasonal shoot‐apical studies.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1964.tb06642.x

出版商:Wiley    

年代:1964

数据来源: WILEY

摘要:

A survey of species of the prunoid genera,MaddeniaandPygeum,and of the genusOsmaroniahas been made. The ovules of all are pendent, campylotropous, and epitropic. In the prunoids, the ovular supply is intimately connected with a central vascular plexus in the base of the carpel; that plexus is absent fromOsmaronia.The prunoid carpels are marked by an extensive degree of fusion among the ovular and wing bundles, by fusion of the sutural margins, by fusion of the 2 integuments of the ovule to a single massive one, and by the presence of 3 or 5 well‐developed bundles in the base. The carpel ofOsmaroniaalso has a strongly fused bipartite ovular supply, separate bundles of which, however, become very much attenuated before reaching the funiculus; it has independent ovular and wing bundles, completely separate carpellary margins, 2 clearly separate integuments in the ovule, and 6 distinctive bundles in the carpel base. At the funiculus, the wing bundle ofOsmaroniais connected with the adjoining weak ovular bundle by a well‐developed vascular branch. Various particularities in the morphology ofOsmaronialend support to its segregation into a unique tribe, the Osmaronieae of Rydberg.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1964.tb06643.x

出版商:Wiley    

年代:1964

数据来源: WILEY

摘要:

The basidia ofExidia 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.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1964.tb06644.x

出版商:Wiley    

年代:1964

数据来源: WILEY

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1964.tb06645.x

出版商:Wiley    

年代:1964

数据来源: WILEY

摘要:

Megasporogenesis and embryo sac development inStellaria mediawere investigated using cytochemical methods for the demonstration of nucleic acids, proteins, and polysaccharides. RNA concentrations were high in the archesporial cells, low in the megaspore mother cell, and increased again to high concentrations with the formation of the megaspore and 2‐, 4‐, and early 8‐nucleate embryo sac. RNA levels were also high in the egg and primary endosperm nucleus but low in the synergid and antipodal cells. Nucleolar size and vacuolation were indicative of RNA synthetic activity. Protein concentrations were parallel in concentration and distribution to those observed for RNA. Polysaccharides were conspicuously absent from all stages except the synergids and nucellar cells. Feulgen‐stained DNA was demonstrable in the antipodal cells, megaspore mother cell, and megaspore cell, but was not visible in the 2‐, 4‐, or early 8‐nucleate embryo sac. Feulgen staining was also absent from the egg and primary endosperm nucleus but was visible in the synergids and antipodals. Histones were difficult to visualize anywhere except in the egg cytoplasm and the nuclei of the antipodals.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1964.tb06646.x

出版商:Wiley    

年代:1964

数据来源: WILEY

摘要:

Since preliminary experimental evidence for the existence of common‐ABheterokaryons inSchizophyllum communewas inconclusive, experiments were performed to test for and to characterize these heterokaryons. Prototrophic mycelia regularly result from the growing together of pairs of mutant strains of identical mating type which carry non‐allelic nutritional deficiencies. Since crossfeeding through a dialyzing Cellophane membrane does not occur, the prototrophic common‐ABmycelia apparently have both parental nuclear types within a common cytoplasm. Hyphal tips isolated from the peripheries of these prototrophic mycelia usually are not prototrophic. The distributions of the parental nuclear types in the subcultured prototrophic mycelia, as revealed by grid sampling, are irregular in pattern and extent; these patterns probably reflect the nuclear ratios in the transfer inocula, as well as the distributions of nuclear types in various parts of the inocula. Since a common‐ABprototroph typically consists of regions containing a single nuclear type as well as regions containing both nuclear types, marked fluctuations of the estimated nuclear ratio occur upon subculture, and many small transfer‐inocula are not prototrophic as they contain only a single auxotrophic nuclear type. The patterns of nuclear distributions in prototrophic common‐ABmycelia are probably maintained by the restriction of nuclear migration.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1964.tb06647.x

出版商:Wiley    

年代:1964

数据来源: WILEY

摘要:

A light and electron microscopic study of interlamellar granules inOscillatoria chalybiawas made to determine their physiological nature.Oscillatoria chalybiawas 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.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1964.tb06648.x

出版商:Wiley    

年代:1964

数据来源: WILEY

摘要:

Acid and basic buffer solutions were applied on slides under cover glasses to thin, hand sections of leaf tissue from normal tobacco plants and equivalent plants infected with tobacco mosaic virus (TMV). The effects on living cells were observed and photographed through phase optics. First, reversible changes and, later, irreversible changes were produced in the cells. Movement of the cytoplasm in a cell could be stopped completely and started again by replacing the unfavorable buffer solution with a favorable medium. Of the organelles, plastids became static first, then mitochondria, and lastly spherosomes. Spherosomes often moved actively when all other organelles were still. Translucent virus monolayers, consisting of particles aggregated side by side, provided markers in the parietal cytoplasm of recently infected cells. Mitochondria generally moved across their surface on the side adjacent to the tonoplast, spherosomes across the surface facing the cell wall. Alkaline buffer solution caused little change of texture in nucleus and cytoplasm or change of form in mitochondria. Clear areas appeared in some plastids. The acid buffer emphasized a cytoplasmic network representing flow lines and eliminated many cytoplasmic vesicles; mitochondria became shorter or spherical in outline, grana of chloroplasts more obvious. Virus inclusions, even the fragile monolayers, were not greatly altered until irreversible changes began. In pH 11–treated cells, the final changes included violent bubbling of cytoplasm, and in pH 2.2–treated cells, snapping of flow lines and coagulation of the cytoplasm. In either case, disintegration of cell structure and virus inclusions was rapid.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1964.tb06649.x

出版商:Wiley    

年代:1964

数据来源: WILEY

摘要:

Pyrenoids of 6 diatoms,Acnanthes minutissima, Cyclotella meneghiniania, Cymbella affinis, Gomphonema parvulum, Nitzschiasp., andSurirella ovalis,were examined comparatively with the electron microscope. All except those ofG. parvulumwere membrane‐limited. The pyrenoid membrane forms a ridge around the pyrenoid ofS. ovalis, C. meneghiniania,andNitzschiasp. Distended double‐disc bands cross the pyrenoids ofC. affinis, G. parvulum, S. ovalis,andA. minutissima;single‐disc bands occur inC. meneghiniania,and 3 disc bands inNitzschiasp. The raphe fissures ofA. minutissima, Nitzschiasp., andS. ovalisdid not contain any cytoplasm or obvious organs of locomotion. InG. 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, inNitzschiasp. andG. 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. InS. ovalisthe 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.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1964.tb06650.x

出版商:Wiley    

年代:1964

数据来源: WILEY

摘要:

New chromosome observations are reported for 30 species and varieties from 4 genera of Ambrosieae:Ambrosia(includingFranseria), Diceria, HymenocleaandIva.Neither polyploidy nor aneuploidy is known in the generaDicorea, HymenocleaorXanthium.Aneuplcid reduction appears to have played a role in the genome evolution of several species ofIvaandAmbrosia.Polyploid species occur in bothIvaandAmbrosiaand polyploid series exist for at least 5 species or species aggregates of the latter. All available evidence indicates that the primitive chromosome number for the tribe isx= 18, differentiation and speciation having occurred at this level, which is here termed diploid. The group, however, must ultimately have been of polyploid origin from forms with x = 9.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1964.tb06651.x

出版商:Wiley    

年代:1964

数据来源: WILEY