orth(Tpteran spermatogenesis 713 



while according to the second diversity must rule under these 

 circumstances. In one instance position of fiber attachment, 

 relation to the spindle, position of daughter chromatids, and 

 method of division remain the same; in the other, these are sub- 

 ject to variation in greater or less degree. It will not be neces- 

 sary to consider at length the disagreements between the views, 

 for, in presenting my interpretation, I have already gone into 

 these matters. There are, however, some specific objections 

 which I should like to urge against the evidence presented on 

 the various points which I have distinguished as characteristi- 

 cally different in the second account, and these I will take up in 

 order. 



a. Position of ring in the first spermatocyte metaphase. Sinety 

 represented this (fig. 131) as being so placed that the central 

 opening becomes visible in lateral view. In this he was followed 

 by Davis and Buchner, while Montgomery and Brunelli fail to 

 show exactly such appearances, but represent extended chromo- 

 somes with their inner ends being pulled past each other. Davis 

 illustrated his interpretation by rope models very clearly. To 

 one familiar with the conditions it is apparent that what de 

 Sinety and Davis saw were oblique views of rings near the end 

 of their division, while Montgomery and Brunelli were con- 

 fronted by lateral, edgewise views of rings which they failed to 

 interpret as such, definitely, because they had not sufficiently 

 studied polar views. I believe this criticism is justified for the 

 polar aspect of the chromosomal complex is so striking and so 

 illuminating that if it had been appreciated it would have been 

 figured. (Brunelli shows in fig. 13 a complex before the full 

 establishment of the equatorial plate.) Few or no complete 

 complexes are represented by these authors — a striking con- 

 trast to the large series pictured by Robertson. To some extent 

 also this criticism lodges against Davis and Buchner. The former 

 represents no polar views in his carefully prepared plates and 

 only two in outline text figures while Buchner shows but one, 

 in which no attempt is made to indicate the structure of the 

 chromosomes. A mere inspection of the numerous drawings 

 and photographs given in this paper will be sufficient to show 



