4S4 E. ELEANOR CAROTHERS 



the original zygotic cell divided into two similar cells, A a B b 

 but that the second cleavage plane passed differently through 

 these two cells so that one gave daughter cells A B and a b, the 

 other A b and a B. Some of these four cells divided oftener 

 than the rest so that more gametes of certain kinds were pro- 

 duced. As to the time of these segregation divisions he says 

 (p. 299): 



Moreover the excess of gametes of parental composition character- 

 izing the coupling- and repulsion-series must certainly mean that the 

 position of the planes of division by which the four quadrants are con- 

 stituted is determined with regard to the gametes taking part in fer- 

 tilization — though the relative positions of the constituents of the 

 cells may perhaps be maintained throughout the history of the tissues, 

 it is easier to suppose that the original planes of embryonic division 

 are determined according to those positions than that their influence 

 can operate after complex somatic differentiation has been brought 

 about. 



Morgan ('15) has shown that the series of facts dealt with 

 by Bateson is the same as those treated by Morgan and his 

 students under the term linkage and that they are open to the 

 same explanation. 



It is evident that if such a somatic segregation as Bateson 

 advocates occurred in Trimerotropis or Circotettix, we would 

 have different types both of spermatogonia and of first sperma- 

 tocytes in the individual, i.e. the metaphases would show 

 varying numbers of atelomitic chromosomes, instead of being 

 constant as I have found them to be. 



..?. Heteromorphism, supernumeraries and reduction in the number 



of chro??wsonu$ 



The more I have studied this unusual group of grasshoppers 

 the deeper has grown the impression that all of its peculiarities 

 are closely interrelated. As was pointed out elsewhere (p. -465) 

 there is some ground for associating the formation of vesicles 

 with a shifting of the point of fiber attachment and also with a 

 weakening of the chromosome at that point. In one animal, 

 division constantly occurred at the point in question. It is 



