86 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
one in type C;. Furthermore the prominent chromomere near the 
polar granules does not seem to be present, except possibly at m (fig. 
107). On the other hand the smaller conjugant resembles those in C, 
in size and otherwise except for the prominent granule already men- 
tioned. We might therefore be led to suppose that the smaller com- 
ponent in C3 is homologous to the smaller one in C; and the two small 
ones in Cy. But if the example at h (fig. 107) be regarded, it will be 
seen that this is a small pair lacking any prominent chromomere near 
the polar granules, and might therefore be thought to be homologous 
with the smaller conjugant in type C3, if it be considered different from 
those in type Ce. However, even if the somewhat questionable posi- 
tion of example h, be disregarded as to homologies, it still must be 
admitted that we have at least three different types of chromosomes 
appearing in these examples of tetrad C. I may again point out that 
there is no chance of making a mistake as to the identity of these 
elements, for the chromosome-pairs B and C are the smallest pairs in 
the complex, and the different types of C are mutually exclusive, that 
is, no two of them are ever found in the same animal. I might further 
add that all the drawings were carefully outlined with a camera 
lucida and the details filled in so as to represent as accurately as 
possible the actual conditions as seen in the microscope. ‘The matter 
of the possible recombination and redistribution of these different 
types is discussed on page 121. 
b. The Accessory Chromosome. 
The accessory chromosome has not been made an object of special 
study here. Since it has been so thoroughly and so frequently de- 
scribed for orthopteran material, it will suffice to give only a brief 
account of it in this connection. In the first place, it should be stated 
that the accessory can be recognized as a distinct chromatic individual 
at practically every stage from the primary spermatogonia to the 
spermatid. The fact that it forms a large and faintly staining vesicle 
or “sac’’ in all the spermagonia except the last, probably accounts for 
the occasional statement that it can be first recognized in the telo- 
phase of the last spermatogonia, where it appears as a condensed mass 
of chromatin, or a chromatin nucleolus. 
Two points deserve to be emphasized: — (1) The accessory, more 
than the other chromosomes, maintains an exclusive individuality in 
nearly all stages. However, it sometimes does become associated 
