Horváth Géza (szerk.): A Magyar Természettudományi Múzeum évkönyve 8. (Budapest 1910)
Soós, L.: A Helix arbustorum hím csirasejtjének fejlődése
330 LH L. SOÓS Helix arbustorum lias another abnormal chromosome, or chromosome-like body, which gets at the beginning of the metaphase of the primary spermatocytes out of the spindle, and then lies in the cytoplasm (Pl. IX., Figs. 6., 8.). I have already mentioned this body. I am of the opinion that this body is identical with the nucleolus. This suggestion cannot be supported by immediate observation, because the nucleolus, as regards its constitution and coloration, at the end of the prophase does not differ from the ordinary chromosomes. There is, however, an important circumstance supporting this suggestion. We have already seen that the nucleolus increases till the end of the prophase into a very large body, and entirely disappears in the young secondary spermatocytes, therefore it must disappear in some phase of the division. There is no trace of its having been dissolved, consequently its disappearance can only be explained by its being cast out into the cytoplasm. The suggestion that the body thrown out might be identical with a true chromosome contradicts all our empirical knowledge and theoretical deductions. The casting out of the nucleolus, however, has already been observed in several cases. B ÜCHNER (18a) observed the phenomenon in Gryllus; DUESBERG (22) is of the opinion that the chromatoid body of the spermatocytes of the rat is identical with the nucleolus cast out into the cytoplasm, and I even conclude from the figures of ARNOLD (3, Pl. X., Figs. 18 and 21) that in spermatogenesis of Hydrophilus piceus a similar process takes place, though ARNOLD interpreted these figures in a different way. I consider the casting out of the nucleolus from the nucleus as the ending of the process which has the purpose of freeing the nucleus from its superfluous chromatin, and thus assist the cell through the depression. When I discussed the phenomena of the depression I mentioned that that explanation had a difficulty, viz., it is difficult to understand the great capacity of absorbing cliromidia of the small cytoplasm of the pachytene cell. It is a very important phenomenon that the nucleolus begins to increase enormously even when the cell is in the pachytene stage, and it takes up more and more chromatin, i. e. it then transforms itself into a chromatin nucleolus. I am of the opinion that this process, the binding of the superfluous chromatin, introduces the balancing of the depression. Upon this hypothesis the difficulties of the explanation mentioned certainly diminish considerably. 6. The development of the spermatozoa. The isolated young spermatids are spherical in shape (Pl. XI., Figs. 1., 3.), those in groups, however, are polygonal (Pl. X., Fig. 9.,
