SYNAPSIS AND CHROMOSOME ORGANIZATION 499 



In this coimection it may be of interest to review the evi- 

 dence on this subject as found in the three forms that I have 

 studied (Phrynotettix, Chorthippus, and Trimerotropis) , and 

 then to compare the opinions of some other investigators, espe- 

 cially those who have studied Chorthippus (Stenobothrus). It 

 will be necessary to consider only the chromosomes of the first 

 spermatocyte, for the behavior in this first division will govern 

 the subsequent behavior in the second spermatocytes. 



In the case of the telomitic chromosomes of Phrynotettix, 

 unequal chromosome-pair C, type C, divided half the time 

 reductionally and half the time equationally. Chromosome-pair 

 B, unequal type, always divided equationally while the equal type 

 behaved in precisely the same manner and presumably also 

 divided equationally. Chromosome-pair A divided equationally 

 with the possible exception of the ring-shaped forms, which were 

 not traced to the metaphase and their behavior not determined. 



In the case of the telomitic chromosomes of Chorthippus no 

 very conclusive evidence is available, but a probable behavior 

 leading to an equational division has been described on a previous 

 page (480). Among the telomitic chromosomes of Trimero- 

 tropis, number 2 (plate 2) exhibited convincing evidence of an 

 equational division, and good evidence for a similar type of 

 division was found for number 4. 



When we come to consider the pairs of atelomitic chromosomes, 

 a decision as to pre- or post-reduction is not so easily reached. 

 The evidence in relation to the chromomere-vesicles found in 

 Chorthippus may be made to favor pre-reduction. In plate 1, 

 it will be remembered, whenever a vesicle occurred it was always 

 single and attached to but one pair of chromatids. This single 

 one might be accounted for in one of two ways: either the two 

 that are found in the earlier stages (figs. 2, 3, and 4, plate 3) 

 have fused together to form a single body, or there may be a 

 normal difference between the two causing one to disappear 

 before the other. In all cases where two are seen, one is shghtly 

 larger than the other. This is well shown, for example, in figure 

 9, plate 3, which presents one of the few cases encountered in 

 which both vesicles appeared at so late a stage. Figures 7 and 8 



