Horváth Géza (szerk.): A Magyar Természettudományi Múzeum évkönyve 8. (Budapest 1910)
Soós, L.: A Helix arbustorum hím csirasejtjének fejlődése
320 LH L. SO ÓS B OLLES L EE , however, holds it possible that some reduction takes place, not indeed during the reduction divisions, but earlier, in these cells which he regarded as spermatogonia. The reduction takes place when the half chromosomes arising from the splitting of the loops are again united. He holds it impossible that during conjugation those halves, which take their origin from the same chromosome should unite ; but with the greatest probability «heterogeneous» halves conjugate, therefore a group of the «ids» separates from every cell. In such a way «a reduction in WEISMANN'S sense can occur, but this reduction is only qualitative, and not quantitative. » I have already had the opportunity of showing the source of BOLLES LEE'S error. I have mentioned that he regarded the young spermatocytes as spermatogonia which really have 24 chromosomes, and did not know the spermatogonia which have 48 chromosomes. As opposed to BOLLES LEE, ANCEL (1, 2) had already shown that the normal number of the chromosomes of H. pomatia is not 24, but 48, so many have the first germ-cells and the first blastomeres. This number becomes reduced during the division of the spermatogonia. The chromatin of the spermatogonia forms first thin loops directed to a determined point of the cell, the threads unite afterwards side-toside, and thus the number of chromosomes becomes reduced to 24. I mentioned when discussing the literature that the phase of the division, in which according to ANCEL the reduction takes place, is not a phase of the division of the spermatogonia, but that of the primary spermatocytes. ANCEL'S observation is in other respects correct, and the reduction really takes place in those cells which he pointed out. The hypothesis that the reduction of the chromosomes must be led back to a parallel conjugation of the early univalent chromosomes, has been very often an object of discussion. "We must also occupy ourselves with this question, because some phenomena in the development of the chromatin of II. arbustorum are so very similar to those of other animals interpreted in the sense of a parallel conjugation that we must reckon with the possibility that the reduction of the species in question takes place in the same way. The literature referring to this question is to be found comprised in several papers, therefore I may pass it by. The partisans of the hypothesis of the parallel conjugation (WINIWARTER, M ARÉCHAL, JANSSENS, BONNEVIE, L ÉRAT, STEVENS, OTTE, SCHLEIP, VEJDOVSKY, A. and K. E. S CHREINER , etc.) claim as evidence the fact that the chromatin of the auxocytes at the beginning of the
