110 The Spermatogenesis of Desmognathus Fusca 



intricately interwoven, the only indication of the segmentation being 

 afforded by apparently free ends protruding on the side toward the 

 idiozome. 



Synapsis. — The beginning of the growth period of the spermatocyte 

 is evidently a time of great importance in the process of spermato- 

 genesis. The spermatocyte possesses chromosomes of one-half the num- 

 ber normally occurring in the mitoses of that species, and this pseudo- 

 reduction has generally been located as occurring in the growth of the 

 spermatocyte. The view, too, that the reduction in number of the 

 chromosomes is only an apparent or pseudo-reduction, is generally ac- 

 cepted. That the chromosomes of the spermatocyte are bivalent and 

 are two joined together end to end, is of course well known and also 

 seems quite generally accepted. The terms introduced by Moore to 

 indicate this pseudo-reduction and the corresponding period, " synapsis " 

 and "synaptic phase," have been used in rather a confusing way. As 

 used by Moore, 95, in his work on the spermatogenesis of Elasmo- 

 branchs, synapsis is equivalent to Riickert's, 93, pseudo-reduction, though 

 Moore apparently does not assume that the chromosomes of the sperma- 

 tocyte necessarily represent two joined together and therefore bivalent, 

 which pseudo-reduction does assume. At the time that this reduction 

 was believed to take place, there occurred in the forms studied by Moore 

 (Scyllium and Torpedo), a peculiar contracted condition of the chroma- 

 tin, causing it to be massed upon one side of the nucleus, and giving 

 the appearance of an artifact. This Moore belieyed characteristic of the 

 synaptic period and to be of general occurrence, and to this phenomenon 

 of chromatin contraction, by a species of m.etonymy, the term synapsis 

 has been transferred by several investigators. For this Moore himself 

 seems partly responsible, since in a later paper, in conjunction with 

 Farmer, 95, he uses the term synapsis as equivalent to " the contraction 

 figure." A distinction between these two uses of synapsis seems to be 

 necessary. The first use is evidently the correct one and is followed in 

 this article. The use of the term in my preliminary communication 

 upon this subject is wrong. The contracted condition of the nucleus, 

 Moore found in the elasmobranchs investigated by him and in Amphibia 

 (the Triton). Brauor, 93, had figured and described the massing of 

 the chromatin upon one side of the nucleus in Ascaris, and Toyama, 94, 

 figures it in the spermatogenesis of the silk worm (Moore). Paulmier, 

 99, describes it in insects (see also Montgomery, 00, p. 354). By botan- 

 ical workers similar figures occun'ing at comparable points in the process 

 of sporogenesis (the maturation period of the spore or pollen mother- 

 cell) have been found in a large range of forms. 



