m'glung: chromosomes of anasa tristis. 371 



number. In plate LXX, figures 1-3, may be seen sperma- 

 togonia! complexes showing this number clearly. 



It is claimed by Foot and Strobell that the number is twenty- 

 two, and they publish four photographs in support of this 

 view. Only one of these represents a stage where the chromo- 

 somes are compact and homogeneous, and this shows twenty- 

 one chromosomes, although in the explanation of the figure 

 the authors state that one of the apparent chromosomes is 

 really two joined at right angles. Since there is no case in the 

 figure where one chromosome is bent at almost right angles, 

 the explanation is not very convincing. The remaining three 

 are of earlier stages, in which the chromosomes have a loose 

 structure that might readily be disturbed in the process of 

 smearing, thus separating one of the larger chromosomes. In 

 two of the photographs Such an interpretation would seem to be 

 entirely justified. Photo 49 is the only one in which there 

 would seem to be any certainty with regard to the number 

 twenty-two. Here it appears as if conditions were normal, 

 and it might be recorded as an instance of twenty-two chro- 

 mosomes in the spermatogonia. 



The conditions regarding the spermatogonia! number may be 

 summarized thus : Paulmier, Montgomery at the time agreeing 

 with him, reported twenty-two spermatogonia! chromosomes. 

 Later, Wilson, working upon Paulmier's original preparations 

 in part, finds twenty-one spermatogonia! chromosomes, and 

 Montgomery, restudying his own material, agrees with this 

 enumeration. Lefevre and McGill report twenty-one sperma- 

 togonia! chromosomes from their own preparations. Foot and 

 Strobell, working upon smear preparations, consider twenty- 

 two to be the normal spermatogonia! number. Miss Pinney, 

 upon examining material from Kansas, Massachusetts and 

 Pennsylvania, and working without a knowledge of others' re- 

 sults, finds twenty-one to be the spermatogonia! number. 

 Finally, from a study of the original material of Paulmier, 

 Wilson, Lefevre and McGill, and Pinney, I myself find in all 

 clear cases, where there is no doubt of the presence of all the 

 chromosomes, that the number is twenty-one. Foot and Stro- 

 bell object to the testimony of Montgomery, and of Lefevre and 

 McGill, on the ground that they reported at one time an even 

 number of spermatogonia! chromosomes and at another an odd 

 number. It must of course be admitted that this weakens their 



