92 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
Going outside the follicle, it is of interest to note what appears in 
the nuclei of the follicular investment. This investment is a thin 
membrane inclosing the follicle, forming the outer of the two layers 
composing the follicular wall. In this membrane the nuclei are very 
much flattened, so that the chromosomes lie nearly all in one plane. 
Figures 111 and 112 indicate the chromatic conditions in two such 
nuclei. It is, I believe, a significant fact that the chromatic masses 
to be found in these nuclei are in number approximately equal to the 
unreduced number of chromosomes found in the spermatogonia. 
Exceptions, it is true, occur; adjacent chromosome-masses may be- 
come intimately associated, or one individual mass may become 
divided into partially separated masses. These nuclei are fully 
differentiated and are destined never to undergo another cell-division. 
They must gradually lose their functions and will finally “die in their 
tracks.”” The different conditions of the chromatin in the different 
nuclei suggests that the process of senescent degeneration may have 
already set in. The important fact still remains, that the individual 
chromosomes have a tendency to remain distinct from each other, 
even in these highly differentiated nuclei in a period not only of ‘rest’ 
but perhaps of senescence. 
D. Summary OF OBSERVATIONS. 
1. The general topographical relations of the different generations 
of male sexual cells in the testes of Phrynotettiz magnus are typical 
for the Acrididae. 
2. For purposes of accurately following the history of the changes 
undergone by the chromosomes from the pachytene stages of the first 
spermatocyte to the time of mitosis, three individual chromosome- 
pairs were selected, each of which possessed characteristics by which 
it could be recognized in all the stages concerned. These three pairs 
were designated, for convenience, “A,” “B,”’ and “C.” A study of 
these three chromosome-pairs showed: — (a) that there is a longi- 
tudinal split in the pachytene stages, which persists into the tetrad 
and later stages (this is called the primary longitudinal split); (b) 
that a tetrad is formed out of a spireme segment by (1) a separation 
along the primary split, and (2) the appearance of a secondary longi- 
tudinal split along the middle of each of the two parts separated by 
the primary split. 
3. Tetrad “A” opens out along the plane of the secondary split, 
