216 KANSAS UNIVERSITY SCIENCE BULLETIN. 



many investigators, the definitive form of the chromosome is 

 used as the basis for determining the direction and sequence of 

 the chromosome divisions. This fact and the danger attending 

 the practice was partly realized b}- Montgomery in his work 

 upon Euchistus (12), for he devotes considerable space to a con- 

 sideration of the prophase segments, but in determining the 

 character of the second spermatocyte division he regards only 

 the formed element. With respect to this he says : "And now 

 a fact may be determined which is of the greatest importance 

 in estimating the morphological value of the second division of 

 the chromosomes. While the latter are still parallel to the axis 

 of the spindle, there may be clearly seen in some cases a trans- 

 verse constriction on some of the chromosomes, so that they 

 already acquire a dumb-bell shape." This constriction is not 

 correlated with any similar one on the prophase elements, and 

 is here observed for the first time. 



In his paper upon Peripatus, however, he definitely supports 

 the contention that it is only in the prophase of the first sper- 

 matocyte that we can learn the construction of the chromo- 

 somes, for he says: "The early stages in the prophase are of 

 the greatest importance in determining the exact constitution 

 of the chromosomes of the first maturation division. 

 Since, then, as has been shown in another section of the present 

 paper, the split of the univalent chromosome of the second 

 spermatocyte is a true longitudinal split, corresponding per- 

 fectly in position with the longitudinal split of the early pro- 

 phase, it follows that the univalent chromosome does not 

 become turned upon its axis to take its place on the equator of 

 the spindle." Orientation is in both spermatocytes based, ac- 

 cordingly, upon planes determined in the prophase. Upon this 

 point Paulmier and Montgomery, as students of Hemipteran 

 spermatogenesis, are now agreed, and their results correspond 

 with observations made upon Orthopteran cells. 



It is upon the sequence of divisions in the spermatocyte that 

 differences now exist between these investigators and myself. 

 In my previous paper I took occasion to elaborate the proof in 

 support of my position regarding the early occurrences of the 

 longitudinal division in the Orthopteran spermatocytes. Mont- 

 gomery follows Paulmier in ascribing the reduction division to 

 the first spermatocyte, and takes no account of my results upon 



