著者

IKEDA Iwaji OZAKI Yoshimasa

出版者

Inperial University of Tokyo

雑誌

Journal of the College of Science, Imperial University of Tokyo

巻号頁・発行日

vol.40, pp.1-25, 1918-05-25

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1. Boveria labialis mainly differs from B subcylindrica STEVENS in lacking the cytoplasmic lenticular mass in the aboral region and in possessing a lip-like appendage on the peristomal disc. Form B. subcylindrica var. neapolitana STEVENS it further differs in the rounded, instead of the pointed shape of the aboral end, and in the larger extension of the oral ciliary spire. 2. The conjugation is isogamic. Two individuals come into attachment with their aboral ends. 3. The micronucleus in the ordinary fission and also the synkarion form four distinct chromosomes in the same way. During the conjugation, the micronucleus divides in two different ways; i.e., its first division is amitotic, while its second and third divisions are mitotic and give rise to numerous chromatin threads instead of four chromosomes. The third micronuclear division seems to be a reducing division. 4. The conjugant meganucleus persists as such in the exconjugant. This persistent nucleus absorbs three quarter-portions of the synkarion. 5. The meganucleus often undergoes fragmentation, leading to its partical degeneration. The phenomenon seems to support HERTWIG'S karyoplasm theory. 5. The meganucleus is occasionally seen throwing off a portion of its chromatin as chromidia, which sooner or later disappear in the cytoplasm. 7. Two sorts of cysts may arise according to the circumstance of the encystment. In the one, the cilia persist, but in a highly modified state, and the cyst contents appear as a roundish polynucleate plasmic mass; in the other, the cilia are lost, and the cyst contents appear as a highly reticulated body consisting of the polynucleate plasm.