10 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



associated with the female, determines the development of 

 females in the next generation. It seems as reasonable to 

 look upon the abnormal maturation as an abortive attempt 

 at normal maturation, its abnormality simply indicating that 

 the egg has not arrived at that stage when complete nuclear 

 adjustment can take place ; has not, in fact, come to the end 

 of its own particular type of metabolic activity. In that case 

 the same phase would be expected to continue and a female 

 to develop in the next generation, as is the case. 



If the tendency for male and female types of metabolism 

 to alternate really exists in protoplasm, and at fertilization the 

 " stronger " germ cell has the casting vote as regards the 

 type of metabolism of the zygote, then it is conceivable that 

 the observed chromosome distribution may run parallel with 

 sex without the chromosomes carrying a " sex factor " at all. 

 It is, of course, highly improbable that any living part of a 

 cell is without its influence on the general metabolism of the 

 cell — the total cell chemistry — and undoubtedly, the chromo- 

 somes play their part. Clearly, too, they are very closely 

 connected with the inheritance of Mendelian characters, but 

 whatever may be their total functions, they need not carry 

 " factors " for either maleness or femaleness, and still could 

 have their observed distribution in the two sexes. It is an 

 established fact that sometimes at cell division a chromosome 

 is lost from one of the daughter cells. Probably in some cases 

 this occurs gradually ; certainly in other cases it occurs 

 suddenly. Seiler 22 and Doncaster 23 have separately reported 

 the loss of chromatin on the equatorial plate during division 

 of germ cells in Lepidoptera, and Doncaster suggests as a possi- 

 bility, that in Abraxas, the loss of a large amount of chromatin 

 from the X chromosome may cause it to become functionless, 

 and so account for the production of unisexual families. A 

 clear case of sudden elimination is provided by Rhabdonema 

 nigrovenosum. 2 * Here, during the maturation of the sperma- 



