M'CLUNG : SPERMATOCYTE DIVISIONS OF THE LOCUSTID.K. 211 



•cross with two nearly equal arms is represented. My interpre- 

 tation of this figure, based upon a great number of careful ob- 

 servations, is that this represents merely an extension of the 

 shorter arms at the expense of the longer ones. In support of 

 this, I have stated that all intermediate stages between a rod 

 with a mere enlargement at the center and a cross with equal 

 arms could be found. How, according to de Sinety 's concep- 

 tion of overlying free elements, could these structures be ex- 

 plained ? 



It is not necessary, however, to have these gradations in 

 order to disprove the theory under discussion. One needs only 

 to carefully examine one of these crosses to be convinced that 

 the two arms lie in one plane where they intersect, and are not 

 superimposed one upon the other as de Sinety shows in his 

 figure 123. Our author clearly realizes the importance of the 

 cross, as may be judged by the following quotation : 



"La croix est de toutes ces figures celle dont la genese peut le plus facilement 

 donner lieu a des interpretations en sens contraire. — Cest pr^cis^ment pour 

 cette raison que nous croyons devoir lY'tudier sptfcialement au point de vue 

 •critique, persuade que, cette figure une fois rattachCe a une th^orie, les autres 

 •doivent en suivre le sort." 



It is unfortunate, therefore, that he was not able to trace the 

 formation of the element in its very early stages and through 

 the various modifications which connect it with the typical rod 

 already described. 



As the simplest modification of this basic form, we find the 

 one where it is evident that the change consists merely in a 

 flexure of the rod at the weak spot in its center. Such forms 

 are shown in figure 14 of my former paper (17) and in figures 

 8, 9 and 11 of this one, but are not illustrated by de Sinety. It 

 occasionally happens that in chromosomes of this character the 

 halves diverge widely at the center, producing the double-Vs of 

 Paulmier, as is represented in figure 14 of my paper upon the 

 Acridida> (17) and in figure 8 of the present one. These struc- 

 tures are not shown by de Sinety and would be difficult to ex- 

 plain in agreement with his conception of the tetrad. 



I have consistently placed great reliance upon the frequent 

 ring-shaped chromosomes in determining the structure of the 

 first spermatocyte elements, and have no occasion to change 

 my opinion of them since examining the work of de Sinety. 



