CHROMOSOME STUDIES 205 



ing to Tettigidea (probably parvipennis). Thej'" repeat and 

 emphasize what has been found m parvipennis and p. pennata. 

 In figures 132 and 134 tardy divisions of certain chromosomes 

 are seen, which may be of significance in the question of reduction 

 and Mendelian segregation, and may have some bearing upon 

 the question of unequal tetrads. They demand further study. 



9. Unequal homologous chromosomes. A female Acridium 

 granulatus was found, in which there were five long chromo- 

 somes among the fourteen instead of the expected four. Later, 

 the same condition was found in a male in first spermatocytes, 

 where homologous chromosomes were separating from each 

 other. This, fortunately, gave a clew as to what the long chromo- 

 somes paired with, for, with one exception, all the chromosomes 

 were present, of normal size, and paired normally. The excep- 

 tion was in the no. I's, which were represented by only a single 

 member, and this paired with the fifth long chromosome (figs. 

 141-145). Anaphase figures (146, 147) showed this small 

 chromosome separating from the abnormal mate (no. 1) and 

 going to the opposite pole. 



After seeing this condition of pairing in the chromosomes of 

 the male, those of the abnormal female were easily paired as 

 follows: two 6's, 5's, 4's, 3's, 2's, two 2x's, one no. 1, and the 

 abnormally large no. 1 . For the female the counts were made 

 in the cells of the walls of ovarioles. 



In the male individual the abnormal no. 1 shows a constriction 

 (figs. 142, 144, 147) at a distance from its distal end equal to 

 the length of the normal no. 1, with which it had been paired. 

 This may possibly be the no. 1 portion of the abnormal chromo- 

 some. (See Chromosome Studies. III.) 



The members of the unequal pair bear no constant relation 

 to the sex chromosome in their distribution to either the second 

 spermatocytes or the sperm cells, as figures 141-147. show. The 

 abnormal chromosome (1) passes as frequently to the pole re- 

 ceiving the sex chromosome as to the pole lacking it. This 

 has nothing to do with the unequal tetrad reported by Baum- 

 gartner ('11) for Gryllotalpa, for that unequal tetrad has since 

 been shown by Pa3^ne ('12) to be a group of sex chromosomes. 



