M'CLUNG : SPERMATOCYTE DIVISIONS OF THE LOCUSTID.K. 217 



Hipp/sens. The objections that I previously urged against Paul- 

 mier's conclusions apply equally well to Montgomery's. Until 

 the chromosomes are traced in a more detailed way through 

 the prophase to the metaphase, I shall consider the presump- 

 tion against the occurrence of the cross-division in the first 

 spermatocyte mitosis. In this I believe that I am justified by 

 the definite proof of my position brought forward in the work 

 upon Ilippiscus. Here, it may be recalled, I observed and pho- 

 tographed in the same mitosis all stages of movement by the 

 chromatids along the plane of the longitudinal split. In addi- 

 tion, I was able to locate definitely the position of the future 

 cross-division in the ring figures, so that it is impossible to 

 mistake the character of the first division in them. These two 

 proofs I consider incontrovertible so far as they apply to the 

 Orthopteran families studied. 



Paulmier judged the planes of the division by the relative 

 lengths of the chromosome axes, but, as I pointed out, this is 

 not conclusive unless it can be shown that they have not 

 shifted, as it is possible for them to do, during the prophase. 

 The value of the ring figure, which is formed at such an early 

 stage that it would be impossible for the shifting of the axis to 

 occur, is here evident. 



Montgomery finds these rings in Peripatus, and realizes the 

 importance of their evidence in determining the planes of divi- 

 sion, but places his conclusions upon a much more insecure 

 footing than those founded upon the Orthopteran cells, because 

 of the criterion used in determining which point represents the 

 junction of the paired chromosomes. The diagnostic feature 

 he uses is the linin connection persisting between the "central 

 ends" of the chromosome, which holds them together until the 

 "distal fibers'' connect with the centrosomes and cause the 

 rupture of the "central" fiber. Since the whole of his elabo- 

 rate theory regarding the continuance of the linin spireme is 

 practically a theoretical conception with little basis in observed 

 fact, the value of such proof cannot compare with that fur- 

 nished by the definitely formed chromosomes themselves in the 

 Orthopteran cells. 



In view of all these facts, I think it must still be held an open 

 question as to which is the reduction and which the equation 

 division in the Hemipteran spermatocytes, although it is not to 



