m'olung: spermatocyte divisions op the locustid.k. 215 



somes, it would appear that the differences have no theoretical 

 value, but that the halving of the mass of chromatin is the 

 process of importance — the standpoint taken by Hertwig. 



"In the two reduction divisions the chromosomes may split 

 by two longitudinal divisions, by two transverse divisions, by 

 one longitudinal and one transverse division, or by one division 

 (longitudinal or transverse) preceded or followed by an elimi- 

 nation division. The facts show already that there is no gen- 

 eral uniformity in the mode of division of the chromosomes in 

 the reduction mitoses. The long line of observations on differ- 

 ent objects show this to be the case, and demonstrates that the 

 expected uniformity does not occur." 



Herein lies the essential conclusion of the work upon Penta- 

 toma, which, so far as a specific retraction is concerned, stands 

 yet. If this be abandoned, then the first work upon the chro- 

 matin structure of Pentatomais practically discredited, for Mont- 

 gomery has definitely retreated from his positions concerning 

 the absence of the "chromatin nucleolus' in the spermato- 

 gonia, the non-occurrence of a longitudinal cleft in the spireme 

 thread, the lack of an equational division of the chromatin in 

 the spermatocyte, the origin of the "chromatin nucleolus," 

 and the fragmentation of the "chromatin nucleolus." In ad- 

 dition to these specifically acknowledged errors, we may infer 

 that Montgomery (12) considers himself at fault in his views 

 upon the production of chromosomes from the "three to six 

 chromatin loops" by breaking apart in the prophase, and upon 

 the occurrence of both longitudinal and cross divisions of or- 

 dinary chromosomes in the same mitosis. The observations 

 recorded in his last paper (15) upon the production of the sper- 

 matocyte chromosomes by the end-to-end union of those in the 

 last spermatogonial division warrant this assumption. 



It follows from all this that we may practically disregard 

 Montgomery's earlier work upon chromosomal structure and 

 take his views as expressed in the later papers (14, 15) as rep- 

 resenting his opinions upon the subject. These later theories are 

 largely the result of his investigations upon Peripatus, but they 

 seem to be carried over and applied to the Hemiptera without 

 essential modifications, and we may regard this concept as ap- 

 plicable to the forms studied by him. 



I called attention in my previous paper to the fact that, by 



15-Kan. Univ. Sci. Bull., No. 8, Vol. I. 



