128 THE BIOLOGICAL PROBLEM OF TO-DAY 



theory and on the doctrine of determinants that I 

 have expressed in this book, I cannot accept the 

 explanation Weismann thus gives of the facts. It 

 is true that Weisniann holds his own explanation 

 to be the only conceivable explanation. ' For there 

 are only two possible a priori explanations of 

 adaptations for the naturalist, namely, the trans- 

 mission of functional variations and natural 

 selection ' (loc. cit, p. 386) ; ' but as the first of these 

 can be excluded' (on account of the infertility 

 of workers and soldiers), 'only the second remains.' 



But are the alternatives really only as Weis- 

 mann suggests ? Is there no choice left for the 

 naturalist ? 



When I was reading his All-sufficiency of 

 Natural Selection, kindly sent me by the author, 

 it came into my mind that I could not accept his 

 dilemma. For the different individuals in the 

 insect states may be explained in a third way in 

 a way overlooked by Weismann. This third ex- 

 planation is nothing more than the subject of all 

 this treatise of mine. It is that, in obedience to 

 different external influences, the same rudiments 

 may give rise to different adult structures. 



I am glad that the same answer has been made 

 to Weismann's All-sufficiency of Natural Selection 

 by two biologists, Herbert Spencer and Emery, 

 simultaneously with mine. Emery, a specialist 

 upon the structure of ants, and Herbert Spencer, 

 relying upon the investigations of several English- 

 men, have sought to prove that the differences 

 between the individuals in the colonies of ants, 



