Horváth Géza (szerk.): A Magyar Természettudományi Múzeum évkönyve 8. (Budapest 1910)
Soós, L.: A Helix arbustorum hím csirasejtjének fejlődése
318 LH L. SOÓS consisting- of fine granules. These threads become later sharper and more definite, and transform themselves into loops. In the next stage they arrange themselves in pairs, parallel to one another, and group in the part of the nucleus directed toward the nebenkern. They later unite side-to-side, and remain for a time in this condition, but soon open out and become scattered through the nucleus. After scattering, the chromosomes shorten and become rod-shaped, and then they represent the definite chromosomes. ANCEL'S statements are for the most part correct, but I consider as erroneous his opinion referring to the side-to-side conjugation of the chromatin threads. I shall discuss this question later. Similarly I must regard as incorrect this part of his statements, according to which the opened loops immediately transform themselves into definite chromosomes. After svnapis, as seen above, the chromatin forms a reticulum which is very similar to that of the cresting nucleus», and the definite chromosomes originate from the granules of this reticulum. P ROWAZEK (98), as appears, has not had the opportunity of observing the division of the spermatogonia, though lie mentions their division, but it is evident both from his description and figures, that he regarded the young spermatocytes as spermatogonia. According to him the chromatin of the spermatocytes first becomes distributed throughout the linin threads, then masses on several points of it, and at last transforms itself into 24 masses which are at the beginning connected by achromatic threads. In the next stage the irregular masses lengthen, and become rod-shaped bodies consisting of granules. Later the rods split, and thus from the 24 chromatin bodies 48 are formed. The 48 bodies finally coalesce into 12, and thus originate 12 tetrades which number is equal to the reduced number of the chromosomes. This process is — according to him — a pseudoreduction in R ÜCKERT'S sense. From PROWAZEK'S statements I must regard as undoubtedly incorrect the part in the sense of which the chromatin forms tetrads. There can occur also the fact that a chromosome may appearently consist of two parallel rods, or four tetrad-like arranged bodies, but such chromosomes do not represent definite chromosomes, but only an intermediate stage in the forming of the chromosomes from the chromomeres. TSCHASSOWNIKOW'S (120) observations are very defective. He has observed the division of the spermatocytes only from the period succeeding the synapsis, and does not mention the former stages at all.
