M 'CLUNG : SPERMATOCYTE DIVISIONS OF THE LOCUSTID.E. 225 



observations upon the behavior of the chromosomes between 

 the spermatogonia and the spermatocytes in objects favorable 

 for study will be awaited with interest. In the meantime it 

 must be conceded that the work upon insect spermatogenesis 

 has at least lent strong support to the theory of the individu- 

 ality of the chromosomes in general and has definitely shown 

 that there is such a thing in some instances. 



(g) Nucleoli. 



Considerable importance is attached by some investigators to 

 the nuclear structures, properly called plasmasomes, that occur 

 in the spermatocytes. It is probable that there are marked 

 differences between the cells of various species in regard to the 

 occurrence of these bodies, for in the Orthoptera they either do 

 not appear at all, or, if present, they are minute and incon- 

 spicuous. This fact would tend to disprove any theory which 

 would attach a fundamental importance to these structures, 

 such as is conceived for the chromatin. The Orthopteran cells 

 do not allow any observations which would add to our positive 

 knowledge of the nucleoli, and I include this brief statement 

 merely for the negative value it may possess. 



(h) Rest Stage. 



In his first paper upon Euchistus, Montgomery assigns an im- 

 portant and conspicuous place to the "rest stage" among his 

 numerous subphases preceding the first spermatocyte mitosis. 

 As a result of his later comparative work upon the Hemiptera, 

 however, we learn that in certain families no trace of such a 

 condition of diffusion on the part of the chromatin is observ- 

 able, from which we conclude that "accordingly such a stage 

 would appear to have no broad significance." It has already 

 been announced that nothing like a rest stage intervenes be- 

 tween the spermatogonia and spermatocytes of the Orthoptera, 

 and the work of most investigators would tend to indicate that 

 it is the exception rather than the rule. In those cases where 

 such a condition of the nucleus exists, it would seem to be true 

 that nothing more unusual than an excessive diffusion of the 

 spermatogonial chromosomes occurs, and this is of hardly suffi- 

 cient importance to receive a special designation. 



The existence of a rest stage between the first and second 

 spermatocytes is also negatived by the conditions found in the 



