The Spermatogenesis in Pentatoma up to the Formation of the Spermatid. 35 



of testicles of salamanders wliich had been well fed during these 

 seasons of the year, in which he found an unusually small number of 

 these cells. But since the syncytia in Pentatoma appear to be pro- 

 duced by over-nutrition, there can be no homology between these 

 structures in this form and Salamandra. 



c) The large generation of spermatocytes. 



In Tropicoris as well as Pentatoma the spermatocytes found in 

 two of the testicular follicles (those numbered 1 and 3 in Figs. 225, 

 227, PI. 5) are considerably larger than those which occur in the 

 other follicles ; and to these may be applied the name "large generation 

 of spermatocytes" to distinguish them from the "small generation", 

 found in the follicles 2, 4, 5 and 6. The spermatocytes of follicle 6 

 average slightly smaller than those of follicles 2, 4 and 5, but this 

 difference is so slight that it does not warrant the recognition of a 

 "smallest generation". The distinction between the large and small 

 generation is then one merely of size, while the various stages and 

 reduction divisions undergone by both are the same, and further, as 

 can be determined without the aid of disassociation preparations, the 

 structure of the spermatozoa is the same in both generations (though 

 there is probably a difference in the size of the latter, a point which 

 could not be determined on sections). The cells of the large generation 

 are marked in the figures by an asterisk opposite the number of the 

 figure. Some few of the spermatocytes in the follicles 2, 4 and 5 

 attain nearly the dimensions of the smallest in follicles 1 and 3, for 

 the dimensions of the individual cells vary in each follicle. Thus the 

 larger generation differs from the smaller only in the greater size of 

 the cells and nuclei: we do not find any differences in the line of 

 development, such as are found in Paludina (Leydig, Auerbach) 

 leading to the formation of the hair-shaped and worm-shaped spermato- 

 zoa. In fact, Pentatoma would seem to be quite unique in the 

 respect of having two types of spermatocytes differing in size alone. 



The spermatogonia up to about the anaphase of the last spermato- 

 gonic divisions have the same dimensions in all follicles of the testicle. 

 Hence cells of the larger generation cannot owe their greater size 

 to the absence of one or more spermatogonic divisions, as is the case 

 in Paludina (Auerbach, '96). The larger size, characteristic for the 

 larger generation, first appears in the synaptic stage of the 1st 

 spermatocytes, and this increase of size of cell body and nucleus then 

 goes on through the telophase and the rest stage. The greater size 



3* 



