STUDIES ON CYTOLYSINS — SPERMATOTOXINS 215 



Male 83 was killed April 11, 1921, and the testes were removed 

 for further study. The right testis was of about average normal 

 size, but the left was very small — not more than one-fifth the 

 mass of the other. Sections were prepared from various regions 

 of each testis. Although the right appeared normal when in- 

 spected superficially, microscopic examination revealed that it 

 was entirely devoid of spermatozoa, spermatids, and secondary 

 spermatocytes. Some of the seminiferous tubules contained 

 only a peripheral layer of spermatogonia and generall}^ these were 

 reduced in number. In such tubules the field lying inward 

 toward the lumen was usually occupied by a more or less loose 

 fibrous reticulum. Other tubules showed numerous primary 

 spermatocytes, but these rarely progressed in spermatogenesis 

 beyond the contraction phase of nuclear change. Many tubules 

 contained degenerating primary spermatocytes with dense, 

 nondescript nuclear masses which stained intensely black with 

 iron-hematoxylin. In some instances the entire microscopic 

 field was filled with an indiscriminate mixture of necrotic 

 nuclear and cytoplasmic substance, staining deeply with iron- 

 hematoxylin. 



Why the critical point at which deterioration becomes mani- 

 fest should lie in the primary spermatocyte and whether it is 

 concerned in any way with synapsis seems unanswerable at 

 present. It is an interesting fact that in mj'- earher studies'' on 

 pigeon hybrids and on guinea-chicken hybrids, abnormahties in 

 nuclear activity likewise came into evidence at the synaptic 

 period of spermatogenesis. In the case of such hybrids I attrib- 

 uted the irregularities to incompatibilities between chromosomes 

 of widely divergent parentage which prevented normal pairing of 

 chromosomes. Such an explanation, even if true for hybrids, is 

 obviously inadequate in the present instance. All that can be 

 said with any assurance is that primary spermatocytes seem to 

 be particularly susceptible to injurious influences of different 

 kinds. 



The left testis of rabbit 83 was entirely devoid of seminiferous 

 tubules. It seemed to have been reduced to a nodule of dense 



» Bui. 22, Univ. of Cincinnati, 1903. Jour. Morph., vol. 23, no. 1, March, 1912. 



