SPERMIOGENESIS OF HELIX ARBUSTORUM. 
3Í21 
growth period forms thin threads which afterwards arrange themselves 
parallel to one another, and in the next stage the thin threads become 
transformed into thick ones. These latter are said to arise through the 
side-to-side union of two thin threads. It is evident that the evidences are 
fairly poor, and are not in proportion to the number of the investiga¬ 
tions made. Since the process of union has not yet been observed in 
living material its proceeding can be concluded only by the séria¬ 
tion of the microscopical figures, therefore the correct explanation de¬ 
pends upon the correct sériation. To be mistaken in this respect is 
very easy, and one of the opponents of the hypothesis, Meves (72), 
really led back its origin to incorrect sériation. According to him not 
the thick threads arise through conjugation of the thin ones, but the 
thin threads originate by the splitting of the thick ones, i. e., the 
pachytene nucleus is older than the leptotene. In H. arbustorum the 
leptotene nucleus is certainly older than the pachytene, so I must con¬ 
clude, upon base of an analogy, that the direction of development 
passes from the thin threads towards the thick ones, and there¬ 
fore, though in some cases the pachytene nucleus is older than the 
leptotene one (Salamandra), this cannot he regarded as a sufficient 
ground upon which to refute the hypothesis. 
More important in this respect are the observations of Popoff 
(94) made in ovocytes of Paludina , and those of Goldschmidt (34) 
referring to Dicrocoelium lanceatum. 
The chromatin of the ovocytes of these animals fii«t forms thin 
threads (leptotene nucleus) which become afterwards thicker and shorter. 
The threads are split very early at the beginning of thickening. They 
become yet thicker in the next stage, their number becomes smaller, 
and their split remains constantly as sharp as it was in the beginning. 
It is very important that they never coalesce perfectly. -— In these 
two cases the thickening of the chromatin threads can be followed 
from step to step (cf. Popoff, PL IV., Pigs. 24—31., Goldschmidt, PL 
VIL, Pigs. 5—9.), but the reciprocal position of the two threads 
constituting the thick thread always remains the same. — This phenome¬ 
non cannot be interpreted otherwise than in the conception of Flem¬ 
ming and Meves, according to whom the thread is already split in the 
early spireme, even if it be then invisible, i. e., the split is preformed 
in the thread — as Flemming expressed himself — and means nothing 
else than a preparation to the next division. It is very important, as 
regards the question, that not only germ-cells, but also somatic cells 
may have split chromatin threads [connective tissue and endothelium 
cells of Salamandra, according to Flemming (29)]. Not less important 
Annales Musei Nationalis Hungarici. VIII. 21 
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