. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. NOTES ON BRANCHIOBDELLA. 107 around each nucleus, thus differentiating the blastophore from the germ cells" (p. 275). In B. varians (Voigt, p. 314 sq.) the blastophore arises in a similar although not identical manner. It is first seen just as the spermatogonia escape from the testis at which time but two or four cells are associated with it. When the spermatogonia divide, a portion of the protoplasm is not en- closed within the cell wall, although it is directly connected with the. cytoplasm of the cell. The young stag
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. NOTES ON BRANCHIOBDELLA. 107 around each nucleus, thus differentiating the blastophore from the germ cells" (p. 275). In B. varians (Voigt, p. 314 sq.) the blastophore arises in a similar although not identical manner. It is first seen just as the spermatogonia escape from the testis at which time but two or four cells are associated with it. When the spermatogonia divide, a portion of the protoplasm is not en- closed within the cell wall, although it is directly connected with the. cytoplasm of the cell. The young stages show the blasto- phore more or less irregular in shape, but as the cells become more numerous it is uniformly spherical. It differs in two par- ticulars from the conditions in Lunibncus : (i) it is found in an earlier stage in the coelome ; and (2) the spermatogonia cells are always distinct in outline from the blastophore, while the earlier stage in Lninbricus is more like a FIG. 3. A camera drawing of a single section of the ovary and nutritive mass. The dorsal granular portion contains a loosely organized nucleus. The ventral non- granular portion is larger in the other sections of it. Branchiobdella instabilia repeats in the formation of the blasto- phore the conditions of B. varians. During the division of the spermatogonia the plane of division has a definite relation to the center of the blastophore. A definite spindle is always present with its long axis tangential to the surface of the blastophore, so that a plane passing through the equatorial plate, if continued, would go through the center of the blastophore. When the. 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, Mass. ). Annual report 1
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
