M 'CLUNG : SPERMATOCYTE DIVISIONS OF THE LOCUSTID.K. 219 



generations as a nucleolar structure, which, however, divides 

 in metakinesis. The most important feature to be noted in 

 this connection is the fact that the structure does not exist 

 as a simple element, but is observed as a number of gran- 

 ules, and that this number varies considerably in different spe- 

 cies. These granules fuse during the "synapsis stage," as do 

 the chromosomes, to produce in the spermatocyte half the 

 number of "chromatin nucleoli" that were present in the sper- 

 matogonia. In this respect the "chromatin nucleolus" differs 

 radically from the accessory chromosome, which has the same 

 valence in both cell generations. The indefinite number and 

 insignificant size of Montgomery's structures are other charac- 

 ters that point to extensive differences between them and the 

 accessory chromosome. 



In his work upon Peripatus, Montgomery states that in re- 

 studying his preparations of Evchistus he observes a continuous 

 linin spireme which involves the "chromatin nucleolus ' : as 

 well as the chromosomes. Here, again, there is a difference- 

 between the Hemipteran element and the accessory chromo- 

 some ; for the latter is entirely free from linin connections in 

 the prophase and is usually surrounded by a hyaloplasmic in- 

 vestment. 



According to Montgomery, also, his "chromatin nucleolus'' 

 usually takes part in both spermatocyte mitoses. In this re- 

 spect there exists an essential difference between his element 

 and that found in the Orthoptera, for, after extended and most 

 critical studies, I have become convinced that only one division 

 takes place in the spermatocytes. In those cases where Mont- 

 gomery admits but a single division, it is stated to occur in the 

 first spermatocyte, while in the Orthoptera the accessory chro- 

 mosome remains undivided here and is halved in the second 

 spermatocyte. 



If, therefore, Montgomery's recent observations are correct, it 

 must follow, I think, that his "chromatin nucleolus" and the 

 accessory chromosome are different structures. I am free to 

 admit, however, that his statements are far from convincing. 

 So much dependence is placed upon the numerical relation- 

 ships of elements that are admittedly very minute, and so little 

 corroborative proof is given, that I entertain serious doubts as 

 to the accuracy of the observations. In this connection I would 



