THEORY OF THE DEVELOPMENT OF ORGANISMS 127 



must adjust themselves so as to be in harmony 

 with them.' 'None of these changes' (p. 318) 

 ' can rest on the transmission of functional varia- 

 tions, as the workers do not at all, or only ex- 

 ceptionally, reproduce. They can thus only have 

 arisen by a selection of the parent ants, dependent 

 on the fact that those parents which produced the 

 best workers had always the best prospect of the 

 persistence of their colony. No other explanation 

 is conceivable, and it is just because no other ex- 

 planation is conceivable that it is necessary for us 

 to accept the principle of natural selection.' 



According to Weismann's conception, ' every 

 part of the body of the ant' (Ioc. cit., p. 326) 'that 

 is differently formed in the males, females, and 

 workers is represented in the germplasm by three 

 (sometimes four) corresponding determinants ; but 

 on the development of an egg never more than 

 one of these attains to value i.e., gives rise to the 

 part of the body that is represented and the 

 others remain inactive.' This structure of the 

 germplasm Weismann attributes to the operation 

 of selection. ' For in the ant state ' (Ioc. cit., p. 326) 

 ' the barren individuals or organs are metamor- 

 phosed only by the selection of the germplasm, 

 from which the whole state proceeds. In respect 

 of selection, the whole state behaves as a single 

 animal. The state is selected, not the single indi- 

 viduals, and the various forms behave exactly like 

 the parts of one individual in the course of ordinary 

 selection.' 



Naturally, from the views on the germplasm 



