Chromosomal Variations in Earivigs 227 



unequal pair passed normally into the metaphase stage. With the con- 

 dition described by Payne in mind, where the larger end of the unequal 

 pair showed a bilobed appearance, it was thought that some such condi- 

 tion might be found here. A careful study of the side views show^ed no 

 such condition, however. It was found that a slightly unequal pair 

 did exist and that this pair stai-ted to divide shortly after the other 

 pairs. Fig-ures 11 and 12 of the prophase show the unequal pair break- 

 ing up into a large bivalent and a small univalent chromosome. Figures 

 17 and 18 shew the small univalent chromosome in the metaphase. The 

 separation of the univalent chromosome as shown in the above figures ac- 

 counts for the normal thirteen count that was found in a small percent- 

 age of cases (figs. 15, 16). Another abnormality that was found in the 

 side views of the first spermatocyte division was the large number of 

 lagging chromosomes. This species differs in this respect from the 

 European species in that the lagging chromosomes were found in the 

 first spermatocyte division only, while in the latter they were found 

 to occur in both spermatocyte divisions. One lagging chromosome was 

 found in the second division but this evidence has been disregarded 

 because of the probable pathological condition of the specimen. This 

 pathological condition was quite evident in other cysts of the same 

 testis. The form of the lagging chromosomes was seen to vary a great 

 deal from a single elongated mass to that of a more or less trilobed 

 condition (figs. 21-28). It was noticed as stated above that the unequal 

 pair divided somewhat later than the other pairs. By tracing this 

 unequal pair from the metaphase to the anaphase the evidence seemed 

 to warrant the conclusion that the lagging chromosomes were these 

 unequal pairs that were dividing irregularly. Figure 2.5 shows an un- 

 equal pair dividing into an upper single mass and a lower mass that is 

 somewhat bilobed. Figures 2.3, 24 and 26 also indicate this condition. 

 Figures. 27 and 28 are serial sections of the same cell in anaphase. By 

 counting the chromosomes in both figures the lower part shows definitely 

 12 chromosomes while in the upper part are 11 chromosomes and the 

 bilobed chromosome that is slightly lagging. If this lagging individual 

 is the unpaired univalent plus one half of the divided bivalent we have, 

 then, 12 chromosomes passing to the lower pole and 1-3 to the upper. 

 This is ju«t the distribution that would be expected with the 2.5 chromo- 

 somes in the spermatogonia! division. That the univalent chromosome 

 becomes attached to one of the autosome pairs causing this lagging in 

 the first spermatocyte division is further evidenced by the condition 

 shown in figures 23 and 26. In figure 23 an enlargement on one side 

 of the lagging chromosome is very noticeable. Figure 26 is a later 

 anaphase than figure 23. Here the lagging chromosome has divided 

 but the parts still lag behind the autosomes. The upper chromosome 

 is much smaller than the lower and the irregular outline of the lower 

 mass resembles the upper part of the lagging chromosome in figure 

 23. One suggestion the writer might offer to account for these lagging 

 chromosomes is that it is determined by the position of the attachment 

 of the small univalent chromosome to the larger autosomes. When 

 the small chromosome becomes attached so as to adhere to both auto- 

 somes the three chromosomes assume the linear arrangement in early 



