SYNAPSIS AND CHROMOSOME ORGANIZATION 495 



The evidence for parasynapsis as it has been presented for 

 Chorthippus and Trimerotropis on the previous pages is very 

 much of the same nature as that presented in the paper on 

 Phrynotettix ('16). The chief differences are as follows: In 

 Phrynotettix three particular first spermatocyte chromosomes 

 were selected for intensive study because they possessed charac- 

 ters which made their identification possible at most of the 

 stages concerned. For these three chromosomes stages in the 

 transformation of the double-thread spireme segment to the 

 tetrad in metaphase or anaphase were traced. In the present 

 study similar stages have been traced for all of the chromosomes 

 in both species. In Phrynotettix the leptotene and zygotene 

 stages were carefully studied and one of the selected pairs of 

 chromosomes traced through these stages. In Chorthippus and 

 Trimerotropis, lepto-zygotene stages have been found which 

 demonstrate the phenomenon of parallel conjugation, beginning 

 at the proximal ends of the threads, just as was found for 

 Phrynotettix. 



In the latter species all of the chromosomes are of the rod- 

 shaped or telomitic type, while in Chorthippus there are both 

 telomitic and atelomitic types and in Trimerotropis there are, 

 in addition to the two types named, heteromorphic pairs with 

 one member telomitic and the other atelomitic. I think the 

 evidence presented shows very conclusively that parasynapsis 

 occurs for all the chromosomes of whatever type in these three 

 species. 



When we consider the papers of others who have studied the 

 male germ cells of various species of Chorthippus (Stenobothrus) 

 we find that not all have expressed an opinion on the subject of 

 synapsis, and among those who have considered the subject, 

 there are some differences of opinion. 



The work of Carnoy ('85), who studied the male germ cells of 

 Stenobothrus along with those of a large number of other Ar- 

 thropods, was of a pioneer kind and did not concern itself with 

 the subject of synapsis. 



Davis ('08) was the first among those who have studied 

 Stenobothrus to consider seriously the subject of synapsis, and 



