WENRICH: spermatogenesis of PHRYNOTETTIX MAGNUS. 119 



eggs, that the chromosomes were quahtatively different. Sutton 

 ('03) in the following year, explained how the behavior of the chromo- 

 somes in matm*ation could be correlated with the behavior of Men- 

 delian characters. He showed: — (1) that the union of clu-omosomes 

 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 Ci in Phrynotettix agrees 

 with that described by Carothers and Robertson. These cases 

 establish the fact that there really is a distribution of chi'omosomes 

 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 Zoolo- 

 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 



