No. 533] INHERITANCE IN COLlAs I'll I LO DICE 275 



the sperms contain no sex determiner, which is presumed 

 to be present in half of the eggs only, then we must 

 imagine that a single quantity of this determiner raises 

 one oosperm to the female condition, while, in the entire 

 absence of it. it is understood that another oosperm pro- 

 ceeds to the development of the frequently more complex 



sex-limited characters devised by Wilson and modified 

 by Castle to express the parallelism between recent dis- 

 coveries in cytology and Mendelian segregation, I do not 

 wish to imply that the symbol X. as applied to Culms. 

 refers to any sort of chromosome. Nor is there, so far 

 as I know, any cytological evidence as to the dominance 

 or recessiveness of the homozygous male condition in the 

 possibly large class of cases like Ah ra.ru s and Cnl'ms in 

 which the female is presumably heterozygous for the 

 sex determiner. 



As Castle, 1909, has shown, there are two categories 

 of cases in sex inheritance: viz.. (A) those in which the 

 female is assumed to be a homozygous dominant for the 

 sex-determining factor (XX), while the male is a hetero- 



only physiologically but presumably even morpholog- 

 ically different. This category is illustrated cvtologicall v 

 by the extreme, case of Anasa, in which one set of sperms, 

 the male-producing, contain only four chromosomes each, 

 while the other, the female-producing, have live, the num- 

 ber characteristic of all the eggs. The second class of 

 < B) is that including Ahnnus and Cnlias. in which 



assuming that the female is heterozygous for the differ- 

 ential sex factor, producing two types of eggs, one des- 

 tined, when fertilized by the sperm of the homozygous 

 male to produce only males, the other only females. 

 Furthermore Castle, following Bateson and Punnett, 

 1908, regards maleness as recessive, the oosperm contain- 



