Studies on the Male Gametophyte in Angiosperms, II
Differentiation and behaviour of the vegetative and generative elements in the pollen grains of Crinum
1937 年 FujiiJubilaei 巻 2 号 p. 920-933
詳細
1937 年 FujiiJubilaei 巻 2 号 p. 920-933
1) The investigations of the pollen development in Crinum-species are reported with special reference to the behaviour of the vegetative nueleus and of the generative cell in their living or fixed state.
2) The primary microspore division occurs invariably along the short diameter of the polten grain, one end of the spindle being free in the cytosome and the other end close to the intine. The daughter nueleus formed an the free end of the spindle becomes the enlarged and inactive vegetative nueleus, while the nueleus forme-d dose to the intine becomes the generative nueleus and is enclosed by a thin wall to form the generative cell. When the Pollen comes to maturity, the vegetative nueleus, being gradually dehydrated, becomes amoeboid in form, while the generative cell is transformed into a spindle-shape and lies free in the vegetative cytosome.
3) The vegetative nueleus begins to increase in size and to lose its chromaticity soon after the primary microspore division. About one day after the division, the nueleus becomes a homogeneously hyaline sphere and is only faintly stained by Feulgen's method. The chromatic substance in the vegetative nueleus seems to have dissolved and diffused homogeneously into the nuclear sap. In the mature pollen grain, the nueleus is amoeboid in shape and is stained by Feulgen's method less than in the above mentioned state, showing a remarkable deerease of thymus nucleic acid. Considering the features mentioned above, the vegetative nueleus is supposed to be a degenerate element.
4) The generative nueleus is intensely stained by ordinary staining methods as well as by Feulgen's at every stage of the pollen development. In the mature pollen grain the nucleus often appears to be in a prophase-like condition, being surrounded by the characteristic sheath of cytoplasm which consists of a hyaline medium and many lipoid-like granules. The origin of these constituents of the generative cytosome has not yet been ascertained.
5) The haploid chromosome number is 11 and the diploid number is 22 in all three plant forms: C. asiaticum, var. japonicur, C. gigas and C. latifolium.
The writer wishes to express his cordial thanks to Dr. Sinotô for his helpful suggestions and criticism throughout the course of this investigation.
