. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. NOTES ON BRANCHIOBDELLA. 109 As the spermatocytes become transformed into the spermatid, the chromatin gradually changes from the reticulate state into a compact, homogeneous mass. The spermatid is a small oval- shaped cell attached by the tip end of the head to the blasto- phore. Between the nucleus and the cell wall in the region farthest from the blastophore, there is a body which takes a basic. FIG. 4. A camera lucida drawing of an ovocyte with the No. 6 comp. ocular and 2 mm. objective. FIG. 5. Prophase of young ovocyte
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. NOTES ON BRANCHIOBDELLA. 109 As the spermatocytes become transformed into the spermatid, the chromatin gradually changes from the reticulate state into a compact, homogeneous mass. The spermatid is a small oval- shaped cell attached by the tip end of the head to the blasto- phore. Between the nucleus and the cell wall in the region farthest from the blastophore, there is a body which takes a basic. FIG. 4. A camera lucida drawing of an ovocyte with the No. 6 comp. ocular and 2 mm. objective. FIG. 5. Prophase of young ovocyte drawn to the same magnification as Fig. 4. Fir,. 6. Metaphase of spermatocyte No. 12 comp. ocular and 2 mm. objective. FIG. 7. Metaphase of spermatocyte showing the relation of the spindle to the nucleus, drawn to the same magnification as No. 4. stain and is the centrosome or centrosornes of the last spermato- cyte generation. The cells become so very small and the cyto- plasm so much reduced that one can not be certain that there are two bodies ; at this stage the body is much larger than the centrosomes during mitosis. The distal portion of the cytoplasm becomes drawn out and forms the tail, at the same time the sperm centrosome elongates forming a connection between the nucleus and tail. This region becomes the middle piece in the adult sperm. The rapid elonga- tion of the tail and nucleus soon renders it impossible to detect the presence of the cytoplasm. During the elongation of the nucleus, it stains more intensely and becomes constricted as if a large number of shallow parallel furrows crossed it at about 90° to the long axis of the sperm. The very tip of the sperm during nearly all of these changes remains in connection with the blastophore. From the quotations cited from Voigt's interpretations of the spermatogenesis of the European Branchiobdella, it is apparent that there are important differences. In a few instances a struc- ture which I regard as the nebenkern a
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
