SEGREGATION OF HOMOLOGOUS CHROMOSOMES 467 



of union of the homologues is correspondingly nearer the bend in 

 the dyad with the long free arm. Photomicrographs of these 

 conditions are shown, figures 22c and 22d (plate 14). As indi- 

 cated by the numbers, these two chromosomes occur in the 

 same individual (plate 4, 22). They are not modifications of 

 the same chromosome, for in numerous instances both are present 

 in a single section of a cell. Figure 23a, from another specimen, 

 shows a tetrad which is homomorphic for the long-armed con- 

 dition of the homologous chromosome shown in figure 22c, while 

 figure 10a is probably the homomorphic short-armed form of 

 the same chromosome from another specimen. At least, this 

 latter individual is homomorphic for the short-arms as may be 

 seen from the drawing of the entire complex (plate 3, 10, chromo- 

 some no. 11). The homomorphic forms of tetrad number 9, 

 shown in 22d, are represented in figures 17a and 106 (plate 14). 

 Chromosome number 9 may also be J-shaped (plate 2, 7) or 

 telomitic (plate 4, 25). 



All possible combinations of the dyads in these two types of 

 heteromorphic tetrads occur and segregate freely in relation to 

 sex. 



In the two heteromorphic types described above, as in the 

 case of chromosome 'C in Phrynotettix (Wenrich '16), we have 

 a visible mechanism whose behavior in the maturation divisions 

 corresponds to the segregation of triple allelomorphs. 



/. Reduced number of chromosomes in Circotettix. Circotettix 

 is the only genus of the Oedipodinae, so far investigated, to 

 have less than the typical number of chromosomes. Numerous 

 counts showed eleven to be the number in the first spermatocyte 

 and twenty-one in the spermatogonia (plate 11, figs. 70a and 

 75). I am not satisfied as to whether the missing chromosome 

 is number 2 or number 3. Plate 10 is arranged to emphasize 

 its absence. The figures are from Circotettix lobatus, but 

 rabula agrees in this respect. It is idle at present to speculate 

 as to whether the chromatin which would have gone to form 

 the missing tetrad has disappeared from the complex or whether 

 it has united with some other tetrad to form an octad such as 

 Robertson ('16) postulates to account for the reduced number in 



