M'CLUNG : SPERMATOCYTE DIVISIONS OF THE ACRIDID/E. 89 



thread. In elaborating this conception, there is no denying that his 

 diagrams are much more conclusive than are his figures. 



The dumb-bells which he represents are nothing more nor less 

 than the U-shaped figures so common to insect spermatogenesis. I 

 am quite at a loss to reconcile his union, by pairs, of the chromatic 

 segments with any real occurrences in the spermatocyte prophases. 



Again, in his interpretation of the completed tetrad I consider 

 Wilcox in error. I have never yet ob.served in Orthopteran material te- 

 trads composed of spherical chromatids. In the AcrididcV, at least, they 

 correspond in structure and method of division to those of Hippiscus. 

 In a few of this author's figures, there are represented chromosomes in 

 the metaphase of the first sjjermatocyte division which bear a general 

 resemblance to those I have found in Hippiscus. Note, in connec- 

 tion with this point. Figs. 20, 22, and 25 (20). In Fig. 9, also, will be 

 found a ring corresponding in structure to those represented in Figs. 

 15 and 15« of this paper. 



In a previous article, I have already called attention to a corre- 

 spondence between Wilcox's "nucleolus" and the body which I have 

 described under the name "accessory chromosome." Further studies 

 have confirmed me in my opinion that these bodies are identical 

 structures. In fact, as observations multiply, the process of sperma- 

 togenesis in the insects seems to approach a type, the deviations from 

 which are only in minor details, corresponding to variations in size 

 and habit of the elements concerned. 



In justice to Wilcox, however, I would fay that the feniur-ruhruia 

 material is far inferior to that furnished by Hippiscus, so that struc- 

 tures quite plainly apparent in the latter would be difficult to discern 

 in the former. I believe that due importance should be attached to 

 the character of the material employed by an investigator, so that 

 statements based upon a study of favorable subjects, other things 

 being equal, should receive credence over those resulting from a study 

 upon less favorable observation material. 



The latest paper by Paulnuer (26) unfortunately reached me after 

 the manuscript of this article was in the hands of the printers. On 

 this account, I shall be unable to accord it the attention it deserves, 

 and shall be obliged to confine myself to a few brief foot-notes. I 

 hope, however, to consider it more at length in a subsequent paper. 



In a recent paper (11) Paulmier discusses the formation and divi- 

 I sion of the tetrads in the spermatogenesis of the Hemiptera. It is 

 gratifying to note that the processes in this order and in the Orthop- 

 tera appear to be essentially the same. So far as I know, Paulmier 

 is the first to accurately describe the early changes taking place in 

 the nuclear thread that result in the formation of the tetrad. These 



