TRANSMISSION OF CHARACTER 207 



on the yellow blossoms of Actinomeris squamosa are 

 green or greenish yellow. Weismann attributes this 

 phenomenon to reserve determinants which he creates 

 for the express purpose of explaining seasonal or 

 sexual dimorphism. 



"The germ," he said, "must thus contain all the pri- 

 mary constituents (Anlagen) of these different 

 forms; and a stimulus produced by the kind of food, 

 by light, by warmth, or by some other external influ- 

 ence, serves sooner or later to start the development 

 of one kind or another, as well as to decide which kind 

 it shaU be." 9 



What enables those stimuli to exert their action, is 

 the previous existence of individual differences be- 

 tween primary constituents, of a preformed adapta- 

 tion, due to natural selection. The determination of 

 the sex in bees and ants is considered by Weismann 

 as good evidence for it. The sexless character of the 

 workers is not directly due, as the Lamarckians think, 

 to the larvae's insufficient supply of food, but to the 

 presence in the ovum (as a consequence of selection) 

 of two kinds of determinants, one corresponding to a 

 rudimentary, the other to a perfect ovary, the former 

 developing when the young larvae receive insufficient 

 food. Nutrition certainly plays an important part 

 but only in an indirect way. Scarcity of food is the 

 stimulus which causes certain determinants to emerge 



o Weismann, The Romanes Lectures, 1894, pp. 52, 53, 



