SYNAPSIS AND CHROMOSOME ORGANIZATION 509 



plasmosome-like chromomere-vesicles adds considerable to the 

 evidence indicating a constant and definite organization of each 

 chromosome. 



D. Summary of conclusions 



1. Parasynapsis occurs in all the chromosomes of Chorthip- 

 pus and Trimerotropis, whether they are pairs of rods, pairs of 

 V's, or heteromorphic pairs. 



2. The pairing begins at the proximal end of the rods and 

 at the apices of the V's and proceeds distally. It is probable 

 that the distalward progress is not uniform, but that the distal 

 ends may occasionally become conjugated before intermediate 

 parts have united. 



3. In the telomitic chromosomes of Chorthippus and in 

 chromosomes 2 and 4 of Trimerotropis there is evidence that the 

 first matm^ation division may be an equational one. The 

 heteromorphic pairs probably divide reductionally. In the case 

 of the atelomitic chromosomes the bulk of evidence favors pre- 

 reduction, but no definite conclusions on this point seems to be 

 possible. 



4. There are probably two types of atelomitic chromosomes, 

 one, found in Chorthippus, consists of compound chromosomes, 

 representing two rods joined at their proximal ends, the other, 

 in Trimerotropis, is a bent rod. This is in agreement mth 

 Robertson's ('16) suggestion. 



5. Chromomere-vesicles are constant in position in the chro- 

 mosomes to which they are attached, and go to support the 

 idea that the chromosomes are constant in their internal 

 organization. 



JOURNAL OF MORPHOLOGY, VOL. 29, NO. 2 



