SYNAPSIS AND CHROMOSOME ORGANIZATION 503 



ner and thus divide reductionally. As a matter of fact, chromo- 

 some 12 in cell D, plate 2, shows a constriction in one pair of 

 chromatids (b) and not at the homologous point in the other 

 pair. This might be considered as evidence that the constricted 

 pair represented one conjugant which showed this pecuUarity 

 without its being shown by its partner, and that therefore a re- 

 ductional division was foreshadowed. The results of Carothers 

 ('17) also go far to support pre-reduction for the pairs of atelo- 

 mitic chromosomes. She finds that for each of the chromosomes 

 1, and 4 to 9 inclusive one of three conditions may exist in 'dif- 

 ferent individuals: (1) there may be a pair of atelomitic chromo- 

 somes, or (2) a heteromorphic pair, or (3) a pair of telomitic 

 chromosomes. Since the members of the heteromorphic pairs 

 separate in the first di\dsion, it is reasonable to suppose that in 

 another individual the two members of a pair of atelomitic 

 chromosomes, both of which were homologous to the one atelo- 

 mitic meniber of the heteromorphic pair, would also separate 

 in the same way. And further, it might be presumed that even 

 the telomitic homologues, when both are present in the same 

 tetrad, would have a similar behavior. The strongest evi- 

 dence, then, in both Chorthippus and Trimerotropis seems 

 to support the pre-reduction hypothesis for the atelomitic 

 chromosomes. 



I have gone into all these suppositions and analogies for the 

 purpose of showing how difficult it is to arrive at any general 

 conclusion with regard to the behavior of the chromatids and 

 the consequent plane of separation at the first division. It is 

 my belief that only in those cases where the two conjugants of a 

 pair can be differentially recognized can the plane of separation 

 in the first spermatocyte di\dsion be absolutely determined for 

 these atelomitic chromosomes. 



The method of analogy is perhaps too generally used in the 

 discussions of the subject of reduction. Gregoii^e ('10) at- 

 tempted, unsuccessfully, to align most of the results published 

 up to the time of the completion of his paper into an agreement 

 on the side of pre-reduction. Davis ('08), taking the V-shaped 

 chromosomes of Stenobothrus as a type, concluded that pre- 



