THE SPERMATOGENESIS OF THE MYRIAPODS. 2OQ 



however, is to be found in the prophase. As I have already 

 noted the longitudinal split is the first made manifest at that time, 

 hence logically would be expected to preceed the transverse 

 division, which does not appear until later. Further proof of the 

 sequence of the divisions is found in the second spermatocyte 

 where, as will be presently seen, a cross division of the chro- 

 mosomes certainly occurs. 



The question as to the sequence of the two spermatocyte di- 

 vision, while probably of not any vital importance, has been the 

 subject of considerable controversy. By far the greater number, 

 however, agree that the equation division comes first, and is suc- 

 ceeded by the reduction division. Ruckert, '92, Hacker, '92, 

 McClung, 'oo, '02, Blackman, '01, P. Bouin, '02, in arthropods, 

 and Bolles Lee, '97, Linville, 'oo, Griffin, '99, Klinckowstrom, 

 '97, Francotte, '97, and Van der Stricht, '98, in other inverte- 

 brates, have arrived at this conclusion. While the opposing 

 view /. e., that the reduction division precedes is held by 

 Vom Rath, '92, '95, Henking, '90, Paulmier, '99, and Mont- 

 gomery, '98, 'oo, '01, in anthropods and Lillie, 'oi, in molluscs. 

 In arriving at this latter conclusion the criterion invariably used is 

 the appearance and behavior of the elements during the two 

 mitoses. But during the metaphase the chromosomes are always 

 so compact that the cleavages shown in the prophase are entirely 

 obliterated, and the manner of division therefore cannot be de- 

 termined with certainty. An example of the likelihood of mis- 

 interpretation of the nature of these divisions is shown by Griffin, 

 '99, TJialasscuia. Here the first division is very evidently longi- 

 tudinal, and upon superficial observation the second also appears 

 to be of the same nature. But when the phenomena observed 

 in the prophase are considered, it is evident that this cannot be 

 true, as an indubitable transverse cleavage was to be seen at that 

 time. Upon further study Griffin shows his first impression to 

 be false, for the second division is in reality a reducing division. 



In all of the investigations with which I am acquainted it has 

 been reported that the longitudinal cleavage is the first to be made 

 evident in the prophase. Then I believe it is but logical to con- 

 clude that this division is completed by the first spermatocyte 

 mitosis, especially when this has been shown to be the case in a 



