WENRICH: spermatogenesis of PHRYNOTETTIX MAGNUS. 79 



figure 86 is of a pair of spermatids in which the accessory does not 

 occur. The diffusion process has here proceeded beyond that shown 

 in figure 85, but the two more deeply staining masses, representing 

 the monads of A and B, can readily be distinguished. 



We may on the strength of this evidence say that the chromosome- 

 pair A can be traced from the spermatogonia to the spermatids, thus 

 demonstrating a case of morphological identity through all these 

 generations and stages. 



2. Chromosome-pair B. — If morphological continuity is the gen- 

 eral rule, and if the peculiarities of the chromosome-pairs B and C 

 are distinctive enough, we should be able to trace the latter as we have 

 traced A. In many stages, however, these smaller pairs are not so 

 easily recognizable as was the pair A, but it has been possible to ob- 

 tain good evidence for individuality even through them. 



I have called attention to a dyad in interkinesis, and a monad in 

 the spermatids, which seem to satisfy requirements for identification 

 as the element B. In figures 80 and 83 (Plate 7), for example, is seen 

 a dyad smaller than A, which stains almost as deeply as the latter. 

 An element with similar properties is to be seen in figures 55 (Plate 5), 

 85 and 86 (Plate 7). This element {B in the figures) has such size 

 relations when compared with A and the smallest element (as seen in 

 figure 80) as we should expect in B; when we consider, further, that 

 in the postspireme stages B stained more deeply than the majority 

 of the other tetrads, the staining qualities exhibited in these later 

 stages should also furnish a means of identification. 



When we look at the spermatogonia! telophases of the same indi- 

 vidual from which figure 63 was taken, that is, one in which the 

 components of pair B are equal, we can readily find a pair of chromo- 

 somes that possesses the chief characteristic by which B was recog- 

 nized in the postspireme stages, namely, the presence of a prominent 

 polar granule at each end and a third not far from the middle, though 

 nearer the distal end. Examples of such spermatogonia! telopliases 

 are sliown in figures 87-96 (Plate 8). A further consideration of 

 these stages is given on page 83. 



The study of cliromosome-pair B in the growth-period has furnished 

 some of the most interesting data on the subject of chromosome 

 individuality that I have secured. An analysis of this pair in its 

 extended condition in the pachytene stages of the first spermatocyte 

 was made for one of the specimens (no. 772) and then comparisons 

 drawn between the conditions in this and those in all the other animals 

 in the series studied. 



