110 , PETEK OKKELBERG 



In the case of the lamprey, it does not seem necessary to tie 

 the question of sex up with chromosomal constitution. It is 

 easy to conceive of every fertilized egg as being practically in a 

 balanced condition as regards sex. Some may be more strongly 

 inclined in one direction and some in the other, and, in so far as 

 this is so, the sex characters may be considered as inherited. But 

 if we look upon the development of one or the other sex as a 

 result of metabolic differences, there is no necessary reason why 

 these differences should be referred to the chromosomal make-up 

 of the fertilized eggs. They may equally well be the result of cyto- 

 plasmic differences in the eggs, and these may be present even 

 before fertilization. If we consider sex from this standpoint, it 

 is not difficult to understand how, as a matter of chance, there 

 might be an equality of males and females when conditions of 

 development are normal, and also to understand how, under 

 extraordinary circumstances, sex might be altered in the develop- 

 ing organism. A cytoplasmic inheritance of the female charac- 

 ters (FF) has been suggested by Goldschmidt for the gypsy- 

 moth. In the case of Sagitta, which is hermaphroditic, it is 

 claimed by Elpatewsky that the development of a primordial 

 germ cell into a male or a female cell is dependent upon the pro- 

 portion of the cytoplasmic body, the so-called 'besondere Kor- 

 per,' that each cell receives. 



Whether we consider the chromosomes or some other part of 

 the cell as responsible for the determination of sex, we must, in 

 the last analysis, think of sex determination as due to the rela- 

 tion between two opposite potencies which are both present in 

 the fertilized egg. In true hermaphrodites, in which male and 

 female germ cells are matured simultaneously, the two potencies 

 are in a state of equilibrium, so that the presence of one is not 

 antagonistic to the other. In protandric and protogynous her- 

 maphrodites the two sexual states seesaw back and forth so that 

 each alternately replaces the other, while in a case like that of 

 Crepidula, which under normal conditions is male in the young 

 stage and female in the older stage, the male potency never reap- 

 pears. In the two latter cases we may think of the antagonism 

 between the two sexual states as the result of the action of cer- 



