Horváth Géza (szerk.): A Magyar Természettudományi Múzeum évkönyve 8. (Budapest 1910)
Soós, L.: A Helix arbustorum hím csirasejtjének fejlődése
33-2 D, L. SOÓS is that synapsis, in which the conjugation is said to take place, is not an exclusive property of the germ-cells, since, according to the researches of MARCUS (63), it occurs also in the cells of the thymus, i. e.. synapsis is only a consequence of a certain condition in cell function. Applying what we have mentioned above to H. cirbustorum, I am of the opinion that the parallel arrangement of the threads of the leptotene nucleus does not mean the introduction to a parallel conjugation, but that the threads have arisen from the splitting of the originally united threads. Though the split disappears temporarily and reappears only later, yet this phenomenon, as I believe, cannot be connected with the conjugation until it be shown that the thread of the leptotene nucleus consists of as many parts as the normal number of the chromosomes, but it is even doubtful, whether the thread is indivisible, or consists of several parts, since the thread of the spireme is convoluted so much that its analysis is almost impossible. From the recent authors only SCHLEIP has found that it consists of several parts, but the majority of observations has given the result that the thread divides into parts only in the pachytene stage. We can regard as determined with certainty that the number of the threads of the pachytene nucleus is equal to the reduced number of the chromosomes. As regards the question of the reduction this is the most important fact. The explanation of reduction depends upon the correct interpretation of this fact. The next question is whether the origin of as many threads as the reduced number of the chromosomes is of equal significance with the reduction, or whether that fact must be explained otherwise? The partisans of the hypothesis of the parallel conjugation are of the opinion that it is only a pseudoreduction, the thread is bivalent, and the true reduction takes place later, during the maturation divisions, when the chromosomes, united during synapsis, separate from one another. Since, however, the hypothesis of parallel conjugation cannot be regarded as correct, the conclusions deduced from it must be erroneous, therefore the answer to the above mentioned question must be that the formation of the segments of the pachytene nucleus is of equal significance with the reduction, and that in spermatogenesis of II. arbustoriun reduction division in W TEISMANN'S sense does not occur. Both maturation divisions are equational in WEISMANN'S sense, which take place, as mentioned above in quite the same manner. The divisions differ from those of the somatic cells only in the respect that the second division very quickly follows the first. The purpose of the quick divisions is to reduce the mass of the chromatin.
