. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. IO6 W. M. SMALLV.'OOL). very similar. The testes are usually somewhat larger than the ovaries and contain more cells. They are located in the sixth post-cephalic somite. Frequently the cells in the testis are pear- shaped as contrasted with the spherical form of the young FIG. 2. A photograph of Branchiobdella pitlchcrriiua showing the post-cephalic segments, the digestive tube and ganglionic swellings. In the sixth post-cephalic segment the two testes are on one side and in the seventh the ovary shows. No evidence was
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. IO6 W. M. SMALLV.'OOL). very similar. The testes are usually somewhat larger than the ovaries and contain more cells. They are located in the sixth post-cephalic somite. Frequently the cells in the testis are pear- shaped as contrasted with the spherical form of the young FIG. 2. A photograph of Branchiobdella pitlchcrriiua showing the post-cephalic segments, the digestive tube and ganglionic swellings. In the sixth post-cephalic segment the two testes are on one side and in the seventh the ovary shows. No evidence was observed to show that nutritive bodies such as Voigt reports for B. varians were present in the cytoplasm ; nor is there a special nutritive cell as in the case of the ovary. In Branchiobdella pitlclicrrima the two testes were found on the same side in one animal (Fig. 2). Associated with the formation of the male sex cells from the time they leave the testes until the spermatozoon becomes fully grown there is a protoplasmic structure, termed the blastophore (Bloomfielcl, 'So, Calkins, '95) in Lnmbricus, and the cytophore (Voigt, '85) in Branchiobdella varians. These two terms seem to refer to the same structure and the more recent term, blasto- phore, will be used in this paper. Calkins traces the formation of the blastophore and finds that it appears before the sperm cells leave the testis. While still in the testis he figures the blastophore as consisting of eight nuclei in an undifferentiated protoplasm. Repeated division of the nu- cleus unaccompanied by the formation of cells gives rise to a multinucleate cell. After a time " cytoplasmic cleavage occurs. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Marine Biological Laboratory (Woods Hole, Mass. ); Marine Biological Laboratory (Woods Hole, Mas
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
