Spore Sac Research Articles

The development of theArchidiumcapsule: clarification of a misconception

Abstract Contrary to an earlier report that the spore sac in Archidium is endothecial in origin, evidence is presented from this earlier report on A. alternifolium and from observations on A. stellatum that the spore sac is amphithecial in origin as in the Bryideae. The retention of Archidium in the Archidiidae is supported on sporophytic evidence.

ULTRASTRUCTURE OF SPOROGENESIS IN THE MOSS, AMBLYSTEGIUM RIPARIUM I. MEIOSIS AND CYTOKINESIS

Emphasis is placed on three aspects of meiosis in the moss Amblystegium riparium (Hedw.) BSG: 1***) nature of the sporogenous layer; 2) prophasic microtubules and polarity; and 3) cleavage pattern. Spore tetrads develop while still encased by archesporial cell walls. The cellular nature of the sporogenous layer differs from the more usual occurrence of free sporocytes released into a common spore sac. Two important events mark the establishment of sporocyte polarity during meiotic prophase: 1) migration of the four plastids to the distal tetrad poles (telophase II poles); and 2) ingrowth of the sporocyte wall in eventual cleavage planes between the tetrad poles. An extensive, plastid‐based microtubule system is associated with organelle migration during the establishment of sporocyte polarity in meiotic prophase. Disruption of the nuclear envelope in prometaphase I occurs at sites opposite the four plastids where microtubules extend from plastid envelope to nuclear envelope. Formation of a cell plate following the first meiotic division results in a dyad, whereas in many mosses meiosis is completed in the undivided sporocyte and is followed by simultaneous cleavage into a spore tetrad. Spore cleavage is accomplished by vesicular coalescence resulting in septa that coincide with the prophasic wall ingrowths.

Ultrastructure of Sporogenesis in the Moss, Amblystegium riparium. I. Meiosis and Cytokinesis

Emphasis is placed on three aspects of meiosis in the moss Amblystegium riparium (Hedw.) BSG: 1***) nature of the sporogenous layer; 2) prophasic microtubules and polarity; and 3) cleavage pattern. Spore tetrads develop while still encased by archesporial cell walls. The cellular nature of the sporogenous layer differs from the more usual occurrence of free sporocytes released into a common spore sac. Two important events mark the establishment of sporocyte polarity during meiotic prophase: 1) migration of the four plastids to the distal tetrad poles (telophase II poles); and 2) ingrowth of the sporocyte wall in eventual cleavage planes between the tetrad poles. An extensive, plastid-based microtubule system is associated with organelle migration during the establishment of sporocyte polarity in meiotic prophase. Disruption of the nuclear envelope in prometaphase I occurs at sites opposite the four plastids where microtubules extend from plastid envelope to nuclear envelope. Formation of a cell plate following the first meiotic division results in a dyad, whereas in many mosses meiosis is completed in the undivided sporocyte and is followed by simultaneous cleavage into a spore tetrad. Spore cleavage is accomplished by vesicular coalescence resulting in septa that coincide with the prophasic wall ingrowths.

The Appendaged Ascospores of Trichomaris invadens (Halosphaeriaceae), a Marine Ascomycetous Parasite of the Tanner Crab, Chionoecetes bairdi

The ascospores of Trichomaris invadens have two long filamentous appendages which are formed early in ascosporogenesis. The appendages are composed of a uniform electron-dense material similar in appearance to the epi spore wall layer and do not contain any filamentous substructure. They develop in the spore sac as structures separate from the spore wall except at the point of attachment to the epispore. The probable function of the appendages for entanglement in substrate material is discussed.

Eccremidium, a Genus of Ditrichaceae New to the Americas

Eccremidium, a Genus of Ditrichaceae New to the Americas

Effect of Light and Other Factors on Capsule Expansion in Funaria hygrometrica

Effect of Light and Other Factors on Capsule Expansion in Funaria hygrometrica

INTERCALARY MERISTEMATIC ACTIVITY IN THE SPOROPHYTE OF FUNARIA (MUSCI).

Marking procedures were combined with anatomical techniques to establish that in Funaria (1) the apical region does not act as an apical meristem contributing to seta growth, and (2) the subapical region contains an intercalary meristem the derivatives of which account for the elongation of the seta. In sporophytes that are 8 mm long there is a distinctive difference in the pattern of cell division in the apical and subapical regions. Large, undivided endothecial cells exist in the apical region, and a central strand of elongated cells occupies the analogous position in the subapical region. The apical region is earmarked to form the operculum and spore sac and part of the apophysis. There is an ontogenetic continuity between the seta and the lower portion of the apophysis, but the uppermost cells of the subapical region do not contribute to seta formation. Instead, these cells and those at the base of the apical region form a transitional zone between apical and subapical influences, and they account for most of the stomates that develop on the apophysis.

Demonstration of the existence of spore sacs around resting spores of Bacillus subtilis and Bacillus globigii.

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Studies in the Gasteromycetes VI

This paper discusses the taxonomic position of Schizostoma, gives an emended description of genus and species and records new data on their distribution. The genus Schizostona was proposed by Ehrenberg in manuscript for a plant collected in Equatorial Africa and named by him Schizostoma laceratum. This genus was not recognized at first and the plant was published by Fries (1829) as Tylostoma laceraturn (Ehrenb.); then Leveille (1846) restored the Ehrenberg genus and listed the plant as Schizostoma lacerumr, but he also included in this genus all species of Tylostoma with irregular mouths. Lloyd (1904) in his discussion of Schizostoma was the first to clearly set forth the true position of this genus and to give an adequate description of its characters. In most of the literature prior to Lloyd's publication it was classed as a Tylostorma. The sub-family, Tylostomoideae, consists of three closely related genera, Tylostoma, Queletia and Schizostoma. All have sporophores with a specialized fibrous, hollow stem which in the unexpanded stage is a short plug included in the base of the spore sac. The stem emerges from the sporocarp on elongation but remains attached to its base in a socket. This socketed stem is a constant character of all three genera; in some species the apex of the stem is very loosely attached and is easily separated from the spore sac as in Queletia and certain species of Tylostoma, while in Schizostoma the stem is firmly attached in the socket to the endoperidium. The main difference between the three genera is their method of dehiscence.

Studies on Ascoidea rubescens: II Cytological Observations

SUMMARY1. For these studies materials collected at Ithaca, New York, in August, 1927, and at Lincoln, Nebraska, in June, 1930–1933, inclusive, were used.2. The hyphae, conidia, and spore sacs are coenocytic but the spores formed in the spore sac are uninucleate.3. The nuclei are much larger in young cells than older cells but all are similar in structure and are characterized by a large nucleolus and little additional chromatic material.4. Characteristic chromatic bodies of several types are conspicuously present in coenocytic cells. Some of these at least arise from degenerated nuclei. The most conspicuous of these is a granular disk to which a homogeneous highly refractive globule is centrally attached. These are evidently the bodies considered specialized nuclei by Varitchak.5. Active growth is apical; new cells are formed as soon as the apical cell has elongated so as to be about a third longer than a typical cell. Cells below the apical region have scanty protoplasm and older cells lose their protoplasmic content.6. All reproductive structures on actively growing thalli are apical, the surface of the thallus often appearing like a vague hymenium.7. Hyphal tips contain up to 20 or more nuclei, young spore sacs up to 40 nuclei, and mature spore sacs up to 160 spores.8. The nuclei for the spores formed in spore sacs arise by simultaneous divisions.9. Spores are first differentiated in spore sacs as lens-shaped masses of denser protoplasm, flattened on one surface and rounded on the other, and are surrounded by less dense cytoplasm.10. The characteristic hat-shape of the endogenously developed spores is due to the fact that the wall of the spore is formed next to the dense cytoplasm of the spore initial on its flat surface and on the outside of a clear layer of gelatinous appearance over the rounded surface. As the gelatinous layer disappears the “brim” of the “ hat “ is formed where these walls unite.11. The spores formed in spore sacs enlarge and become two to several nucleate before forming germ tubes. They give rise to coenocytic hyphae either directly or after fusions.12. Conidia of all types are multinucleate. They give rise either to conidia by budding or to coenocytic hyphae.13. Nuclear divisions in the sporangium are probably mitotic, and probable stages are discussed. Similar figures were occasionally observed in vegetative cells. There are also some indications of amitosis.14. The spore sac is probably an apogamously developed ascus.15. These studies indicate that Ascoidea is a true Hemiascaceous fungus closely related to Dipodascus and Endomyces. The term hemiascus can well be applied to such asci.The writer wishes to extend thanks to Prof. H. M. Fitzpatrick, of Cornell University, for his continued interest, and for suggestions made during the progress of these studies and after reading a first draft of this paper; to the Michigan Biological Station for laboratory facilities and courtesies during the summer of 1930; and to T. J. Fitzpatrick for editing and proof reading the paper.

Studies on Ascoidea Rubescens—II Cytological Observations

1. For these studies materials collected at Ithaca, New York, in August, 1927, and at Lincoln, Nebraska, in June, 1930–1933, inclusive, were used.2. The hyphae, conidia, and spore sacs are coenocyt...