246 WM. REES B. ROBERTSON 



These unequal tetrads behave very much Hke the tetrads of 

 the two other small pairs of chromosomes of these twenty-three- 

 chromosome grasshoppers. If we may assume specific individual- 

 ity for the members of each of the twenty-two pairs of autosomes 

 in the subfamilies of this group of grasshoppers, then we may 

 draw the conclusion that the tetrads of at least seven of the 

 eleven pairs of autosomes divide reductionally in the first matu- 

 ration division. This number is reached by counting Carrothers' 

 ('14) one small pair and the six pairs associated in the V's of 

 Chorthippus, leaving out of the enumeration the V's of Hes- 

 perotettix and Mermiria. 



A fourth case which supports my contention is that of the 

 multiple V-chromosomes of Hesperottetix and Mermiria, just 

 mentioned, which McClung ('05, '14) found to divide reduction- 

 ally in the first maturation division. In Hesperotettix one V 

 occurs in the spermatogonia! divisions. One limb of this V 

 is the sex chromosome, the other limb an autosome. In the 

 first spermatocyte the rod-mate of the autosomal arm becomes 

 paired with that arm and may be seen separating from the V 

 in this division. Something similar occurs in Mermiria, except 

 that there are two autosomes, instead of one in the form of a V, 

 associated with the sex chromosome. The autosomal part of 

 this compound probably separates from its autosomal V mate 

 in the first maturation division. 



From the many instances which I have here given, it seems 

 to me the inference may possibly be drawn that all autosomal 

 tetrads will be found to divide reductionally in the first matura- 

 tion division. 



3. The question of synapsis 



1. Is synapsis a fact? Do chromatin elements actually conju- 

 gate or otherwise become associated two by two? I am assured 

 of the occurrence of synapsis from the behavior of the V-chromo- 

 somes of Chorthippus, of Jamaicana and of Hesperotettix, and 

 from the behavior of the unequal homologous chromosomes of 

 Tettigidea parvipennis, Acridium granulatus and other species. 



