ai be BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
we must at the same time admit a high degree of individuality for the 
autosomes. 
3. Plasmosomes and nucleoli.— One of the most puzzling problems 
that cytologists have to deal with is the behavior and function of the 
so-called ‘plasmosomes’ or ‘nucleoli.’ They apparently exhibit such 
a variety of reactions to methods of technique, and exhibit such 
varying relationships to other structures in the cell, that it is almost 
hopeless even to attempt to classify them. That they play some 
important réle in the physiology of the cell, there is not the slightest 
doubt, but what that réle is, or what relation they bear to the question 
of chromosome-individuality, are problems that are far from a solu- 
tion at the present time. 
In my description of the tetrads A and B, I called attention to a 
peculiar modification of one of the terminal granules of each. I 
emphasized the fact that, in the case of tetrad A, this modified granule 
furnished a means of identification for this element. Just what the 
nature of this modification is, I cannot state definitely, but in the 
pachytene stage it has the appearance of an expansion of a previously 
condensed granule, and I have so treated it in my description. The 
similar condition in B appears to arise in the same way, but in this 
case there seems to be a more definite boundary to the modified gran- 
ule, which thus resembles the plasmosomes, or “ vesicles,’ described 
by Carothers (713). The expanded granule of A is usually not homo- 
geneous, some areas within it appearing more dense than others. This 
condition probably foreshadows that seen in the postspireme stages, 
where it appears more like a collection of small granules, typically 
three in number. Miss Carothers described the ‘vesicles’ that she 
found as being attached to spireme threads, and in some cases to 
specific threads. | Furthermore, she found that the occurrence of the 
vesicles extended to several species, and, in some species, through 
several generations of cells. I am indebted to Dr. McClung and to 
Miss Carothers for the privilege of looking over some of the material 
studied by the latter, as well as for the opportunity of studying slides 
of other species; I can confirm Miss Carothers’s observations, and can 
add that these so-called ‘vesicles’ are present in nearly every species 
of grasshopper that I have studied with this object in view. 
I believe that the modified granules in Phrynotettix can be homol- 
ogised with the ‘plasmosomes’ of other species. I would especially 
call attention to the fact that these structures are always attached to 
chromosomes, and that, in Phrynotettix, at least, they always involve 
a certain part of the chromosome to which they are attached. I 
