80 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
Figure 58 (Plate 5) shows the element during the zygotene stages — 
as indicated by the incompletely conjugated pair of threads near the 
middle of the figure — in a condition of complete parallel association 
for the two conjugants, but a condition in which the members of the 
pairs of granules, the chromomeres, are distinct.. A close examination 
of this spireme of B discloses a series of chromomeres in addition to, 
and smaller than, the three already mentioned as characterizing the 
element. 
For convenience in description the more prominent granules or 
chromomeres will be given separate designations. The five granules 
which I wish to mention more particularly will be numbered in order 
from the proximal (no. 1) to the distal end (no. 5, figure 58). I shall 
also call attention to the two pairs of small granules between numbers 
3 and 4 and to the two pairs of still smaller ones between 2 and 3. I 
should not omit to direct attention to the series of granules between 
numbers 1 and 2 and between numbers 4 and 5, but detailed considera- 
tion of those already mentioned will probably suffice for the purpose 
in view. 
I was at first impressed by the constancy in relative size and posi- 
tion with which some of these granules recurred in different examples 
of B and at different stages in a single individual (no. 772). It then 
occurred to me to compare the same element at about the same stage 
for all the thirteen animals from which material was available. Figure 
97 (Plate 8) is the result, each of the separate drawings having been 
taken from a different animal. The constaney with which the minute 
details of size and arrangement of the parts of this pair were repeated 
in all of the individuals was surprising. Not only are the five more 
prominent chromomeres repeated in approximately the same relative 
sizes and positions,— as shown in figure 97, where corresponding 
granules are connected by dotted lines,— but there is likewise a strik- 
ing correspondence in the more minute details. For example, the 
segment between the granules numbered 3 and 4 always contains two 
pairs of granules of about the same relative size, though they vary 
somewhat in relative position. On the other hand, the segment be- 
tween 2 and 3 is characterized by the entire absence of any prominent 
granules. In some cases, however, as in f, 7, and k, figure 97, granules 
can be made out in this segment, and when this is possible there are 
always two pairs of very small ones in the same relative positions. 
It is true that there are some variations in the appearances of the 
segments between granules numbered 1 and 2 and between 4 and 5, 
as well as differences in the actual size of the numbered granules. 
