ISSN:0368-2927    

DOI:10.1111/j.1095-8339.1990.tb00897a.x

出版商:Blackwell Publishing Ltd    

年代:1963

数据来源: WILEY

ISSN:0368-2927    

DOI:10.1111/j.1095-8339.1990.tb00897.x

出版商:Blackwell Publishing Ltd    

年代:1963

数据来源: WILEY

ISSN:0368-2927    

DOI:10.1111/j.1095-8339.1990.tb00898.x

出版商:Blackwell Publishing Ltd    

年代:1963

数据来源: WILEY

摘要:

SUMMARYIn the course of their development the protonemata ofFunaria hygrometricaproduce two different substances which diffuse into the substrate. In the chloronema a thermo‐labile growth‐promoting substance is formed. In the caulonema, after about 10 days, a substance is produced which is thermostable and soluble in amyl alcohol, which can be dialysed, and which functions as a growth inhibitor. Both substances also influence bud formation. This is at an optimum only when there is a certain balance between these two substances.This promotion is fundamentally different from that brought about by treatment with kinetin, because kinetin can function only as an additional factor in promoting bud formation. Very probably it acts as an agent which creates centres of attraction toward which morphogenetic substances are drawn. This assumption is supported by the fact that kinetin cannot be transported and therefore has no ‘after‐effect’. It probably functions only in the caulonema cell it penetrates. It converts every caulonema cell into a ‘rea

ISSN:0368-2927    

DOI:10.1111/j.1095-8339.1990.tb00899.x

出版商:Blackwell Publishing Ltd    

年代:1963

数据来源: WILEY

摘要:

SUMMARYExperiments on the germination of the spores ofFunariahave established the following.1Some growth substances such as vitamins slightly promote the geotropic response of germinating spores in darkness.2Glucose, even in concentrations as low as 10 mg./L, strongly stimulates the geotropic response.3Light (at an intensity of 1000 lux and more) strongly inhibits the geotropic response. This effect is probably phototonic and can be partly counteracted by glucose.4The nature of the phototropic and geotropic reactions of chloronema is variable, and depends to a certain extent on environmental influences.

ISSN:0368-2927    

DOI:10.1111/j.1095-8339.1990.tb00900.x

出版商:Blackwell Publishing Ltd    

年代:1963

数据来源: WILEY

摘要:

SUMMARY1Studies on the physiology of antheridium formation in ferns are reported. They are based on Dopp's demonstration of a substance controlling the initiation of these organs. The substance is active toward many if not all species of the family Polypodiaceae but inactive towards the species investigated of the families Schizaeaceae, Osmundaceae and Cyatheaceae.2Studies on unresponsive species led to the demonstration of a factor which controls antheridium formation inAnemia phyUitidis(Schizaeaceae), but is inactive towards the species used to assay for the factor active in many polypodiaceous species. InLygodium japonicumthe studies indicate that antheridium formation is controlled by still another substance, even though this species also belongs to the Schizaeaceae.3The prothaUi of the polypodiaceous speciesOnocka sensibilisrespond to the active substance at a young stage of development, but become unable to respond to it soon after they attain heart shape. This loss of sensitivity takes place within less than 2 days. Once insensitive, the prothaUi fail to respond to the active substance even if they are supplied with a concentration 15,000 times higher than that sufficient to bring about a response in prothaUi just 2 days younger.4Surgical studies performed by Dopp indicate that the meristem of the maturing prothaUus begins to elaborate a substance that imposes this loss of sensitivity.5An hypothesis is put forward that the antheridial factor acts by removing a block to antheridium formation.Certain of the author's investigations were supported in part by a research grant (NSF G‐15114) from the National Science Foundatio

ISSN:0368-2927    

DOI:10.1111/j.1095-8339.1990.tb00901.x

出版商:Blackwell Publishing Ltd    

年代:1963

数据来源: WILEY

摘要:

SUMMARYA form of prothallus without a meristem was investigated by methods involving cross‐ and self‐fertilization. Analysis of the spores from the resulting sporophytes showed that control of the character was not directly attributable to the action of nuclear genes. A hypothesis of heritable cytoplasmic units is presented to explain the resu

ISSN:0368-2927    

DOI:10.1111/j.1095-8339.1990.tb00902.x

出版商:Blackwell Publishing Ltd    

年代:1963

数据来源: WILEY

摘要:

SUMMARY1If in mosses in which sex is determined phenotypically gametophytes are regenerated from male or female tissue, the sex‐determination in the regenerated gametophytes may take one of two forms:(i)Following the de‐differentiation involved in regeneration, the genetically fixed balance of sex‐determination is restored (e.g.Funaria hygrometrica).(ii)Despite the de‐differentiation, the balance of sex‐determination is disturbed. The changed balance either slowly returns to normal or remains permanent. Examples of this behaviour seen in the Splachnaceae are the subject of this report.2In conditions in which the tendency to femaleness is progressively weakened, the male tendency eventually becomes paramount, and stable male plants arise.3Male plants may be derived from females in the same way even in a species where sex‐determination is genotypic (e.g.Splachnum rubrwm).The mechanisms are considered to be similar.8. rubrumyields stable dwarf males which rarely produce motile sperma‐tozoids.4Stabilization of the male sex tendency is always preceded by a labile determination phase.5As the Splachnaceae prefer organic materials in their natural habitat, their metabolism may have heterotropic features, probably concerned with specific processes during sexual maturation. This may facilitate the suppression of femaleness in pure culture.6It is not yet clear whether stabilization involves cytoplasmic or chromosome change. The lability of intermediate kinds of sex‐determination militates against gene mutation.7Experiments on the stabilization of the male tendency inEquisetumare s

ISSN:0368-2927    

DOI:10.1111/j.1095-8339.1990.tb00903.x

出版商:Blackwell Publishing Ltd    

年代:1963

数据来源: WILEY

摘要:

SUMMARY1The morphological nature of the tissue regenerating from, the sporogonium of a moss depends upon the physiological age of the regenerating zone. After the sporogonium has attained a certain stage of ageing, only protonema is formed, irrespective of the zone.2If the regeneration is carried out in the tip region of very young sporogonia, still largely embryonic, factors influencing differentiation pass into the regnerated tissue.3Tissue regenerated from the extreme tip retains embryonic features and consists of undifferentiated, apolar, callus cells.4In the subsequent zone, which later on gives rise to the apophysis, other factors are present, and the regenerating tissue gives rise to new setae.5The factors responsible for controlling the differentiation of tissue regenerating from the meristematic zones cannot be detected in the subsequent extension zone by regeneration experiments. Some influence persists, however, in the intermediate transition zone, and it is transmitted to and propagated in protonema arising in this region. Such protonema in certain conditions give rise to sporogonia apogamously.6Although callus cultures give rise to protonema in darkness, a specific differentiation factor is present since callus is invariably reformed on illumination.7All the forms of regenerated tissue (callus, that giving rise to setae, and protonema giving rise to sporophytes) can be maintained in culture. In a strain of hybrid origin, the stability of the seta form in culture is so high that it is comparable with the independent sporophytic regeneration of a higher archegoniate plant.8The callus and seta forms regenerated from the sporophyte have marked heterotrophic tendencies. In addition gametophyte and sporophyte produce secondary plant products differing qualitatively as well as quantitatively.

ISSN:0368-2927    

DOI:10.1111/j.1095-8339.1990.tb00904.x

出版商:Blackwell Publishing Ltd    

年代:1963

数据来源: WILEY

摘要:

SUMMARY1It has been shown by staining techniques and by autoradiography that the cytochemistry of the eggofPteridium aquilinumis strikingly different from that of the somatic cells of the gametophyte. Deoxyribonucleic acid is present in both nucleus and cytoplasm of the mature egg, and in comparison with that of a somatic cell the cytoplasm of the egg contains large amounts of ribonucleic acid and basic proteins.2Examination of ultra‐thin sections of archegonia by means of the electron‐microscope shows that during oogenesis the old organelles descended from those of the spore degenerate. The mature egg contains numerous new organelles and there is evidence that some at least of these are generated from the nucleus.3Relationships are suggested between the ultrastructural and cytochemical peculiarities of the egg, and the possible significance of these peculiarities in relation to the morphological alternation in the life cycle is discus

ISSN:0368-2927    

DOI:10.1111/j.1095-8339.1990.tb00905.x

出版商:Blackwell Publishing Ltd    

年代:1963

数据来源: WILEY