214 KANSAS UNIVERSITY SCIENCE BULLETIN. 



(d) The Spermatocyte Divisions. 



I approach a discussion of Montgomery's conclusions regard- 

 ing the form of the chromosomes in the first spermatocyte, and 

 the sequence of their divisions, with considerable hesitation, 

 because of the difficulty I experience in appreciating his exact 

 position. This is due, not to any lack of positive statements on 

 his part, but to the partial contradictions that result from his 

 frequent changes of opinion. The most important statement 

 in his first paper upon Euchistus reads as follows : "From the 

 Testing stage of the first spermatocyte to the formation of the 

 spermatid, there is absolutely no longitudinal division of the 

 chromosomes. I have studied hundreds of nuclei in these 

 stages, and at the first with a hope of finding a trace of such a 

 process, but observation shows that all divisions of the chro- 

 matin elements are transverse divisions." 



This would certainly seem to be as strong a stand as one 

 could take upon the subject, but in later papers Montgomery 

 assumes with equal assurance the opposing position, which 

 holds for a longitudinal division. Regarding this he says : 

 "During the synapsis stage the chromosomes become split 

 longitudinally, as was first shown by Paulmier (1898, 1899) for 

 Anasa — a process that I had overlooked (!) in my former 

 paper (1898)." Throughout his later investigations this hy- 

 pothesis serves as the basis of all his theories, and the careful 

 longitudinal division of the thread is assigned an important ro } e 

 in the maturation process. So far as positive assertions to the 

 contrary are concerned, a general acceptance of the theoretical 

 importance attaching to this act is to be supposed. 



Notwithstanding this, I find nowhere in his later writings 

 any statement that he abandons the conception formerly enter- 

 tained regarding the non-importance of the longitudinal cleav- 

 age. This attitude is indicated in the following language : 

 "If it can be proved that the mode of division of a chromo- 

 some, i. e., the axis of the line of division, is merely a function 

 of its chromomeres, then it would be of no theoretical value 

 whether the division be longitudinal (equation) or transverse 

 (reduction) . But it happens that the postulated difference 

 forms one of the main premises of Weismann's theoretical 

 superstructure. On account of the differences observed in dif- 

 ferent objects in regard to the modes of division of the chromo- 



