WENRICH: SPERMATOGENESIS OF PHRYNOTETTIX MAGNUs. 119 
eggs, that the chromosomes were qualitatively different. Sutton 
(703) in the following year, explained how the behavior of the chromo- 
somes in maturation could be correlated with the behavior of Men- 
delian characters. He showed: — (1) that the union of chromosomes 
of diverse origin into pairs and their subsequent separation in one of 
the maturation divisions would insure to every gamete one of every 
kind of chromosome in the series: (2) that if the law of chance were 
operative in the orientation of the pairs on the maturation spindles, 
every possible combination of male and female chromosome could 
result; and (3) that such a recombination according to the law of 
chance would account for the transmission of Mendelian characters, 
if the chromosomes retained their individuality and really were the 
carriers of the qualities. 
This work of Sutton has been generally accepted as proving the 
correlation assumed, but it remained for Carothers (’13) to demon- 
strate that the law of chance actually does operate in the distribution 
of the chromosomes in the maturation spindles. In the case of the 
unequal tetrads described by her, it was shown that either the large or 
small member of the pair may go to the same pole as the accessory 
chromosome, which, as usual, was found to go to one pole undivided. 
Moreover, it was found that the ratio between the two results of 
distribution was approximately one to one. Robertson (’15) has very 
recently published some of his work on the Tettigidae, where he has 
found the same rule to hold for the unequal pairs that were present 
in his material. The behavior of tetrad C, in Phrynotettix agrees 
with that described by Carothers and Robertson. These cases 
establish the fact that there really is a distribution of chromosomes 
in the maturation divisions according to the law of chance. 
A further consideration of the cases of unequal tetrads in Orthop- 
tera will show in how far the theoretical possibilities as to chance 
distribution have been realized. Baumgartner (’11) in reporting his 
results on Gryllotalpa borealis before the American Society of Zodlo- 
gists, stated that he found in the first maturation mitosis an unequal 
pair of chromosomes, of which the larger dyad always went to the 
same pole as the accessory. Payne (’12) found the same conditions 
in this species of Gryllotalpa. He regards the large member as 
possibly associated with the accessory to form a sex-group, similar to 
the groups in Conorhinus and Fitchia (Payne, ’09), or in Thyanta 
(Wilson, ’10), with the exception that in Gryllotalpa the grouping 
occurs in the first spermatocyte metaphase instead of the second. 
Payne suggests that the chromosomes instead of following a haphazard 
