WENRICH: SPERMATOGENESIS OF PHRYNOTETTIX MAGNUS. 81 
These variations may be due to one or more of several causes: — (1) 
Differences arise on account of slightly different reactions to the 
fixatives and stains. (2) There is a tendency for adjacent granules to 
fuse, thus causing apparent variations in number and relative size. 
(3) There is a slight difference in appearance at different stages. (4) 
The different positions assumed by the element with reference to the 
optical axis of the microscope may account for some variation in 
appearance. (5) Some individual variation from animal to animal 
might be expected. ) 
It will be noticed that the distal granule (no. 5) is single in all the 
individuals except those represented at b and c, where it is double. 
This is in accordance with the statement previously made (page 70) 
that chromosome-pair B is unequal in eleven and equal in only two 
of the thirteen animals studied. It will also be noticed that the 
granules at the proximal end (no. 1) frequently become associated 
with other polar granules in a composite granule (a, h, 2, 7, /, m, fig. 97), 
and that with one exception (f) the distal end is free. The formation 
of composite granules is a characteristic feature of this material, as 
already noted on page 64. 
One of the granules of the proximal pair (no. 1) of individual f, 
figure 97, is seen to be enlarged and less deeply stained than its mate. 
Another example may be seen at k. I believe this to be an example of 
a modification similar to that described in connection with the distal 
granules of the pair A (p. 66). In B, this condition appears with 
much less frequency, for in a count of 84 cases taken at random from 
one individual only 14 (162%) had one of the granules in the expanded 
condition. This modification may persist into the tetrad stages, as 
was the case with A. No case was found in which both granules were 
expanded. 
In order to test the variability of the details of constitution of the 
element B in a single animal, a study was undertaken with this object 
in view. Sixteen drawings (fig. 98, a—p) were made of examples taken 
at random from a single slide. Comparison shows about the same 
degree of constancy in the composition of the elements here as in the 
set from different animals. Some of the variations may be pointed 
out. For example, the relative lengths of the segments 1-4 and 4-5 
in example a, figure 98, are somewhat different from those in example 
h. I think we may assume that the spireme threads possess some 
elasticity and that the variation in arrangement, association, and posi- 
tion of the several segments of the spireme may frequently bring about 
stresses which may stretch some of the threads or parts of threads to a 
