* iw THE BIOLOGICAL PROBLEM OF TO-DA Y 



V & 



does this, what becomes of his hypothesis that the 

 ''[several castes are constitutionally distinct, and 

 </ result from the operation of natural selection ?' 

 JjjtfS' My course of thought leaves me with little to 

 add to this criticism by Spencer. In this case, as 

 in many others that I have pointed out, Weismann 

 makes his usual mistake. He incorporates in the 

 rudiment what really are stimuli coming from 

 external conditions during the process of develop- 

 \ jt-ment; he makes a grave confusion between the 



LI i rudiment and the conditions of its development. 

 r iy . f , . 



r . In my view, in these cases ot polymorphism in 



'"the colonies of insects Nature exhibits a series of 

 most important experiments, and their plain 

 meaning is that the same germinal material, when 

 subjected to different external influences, may 

 roduce very different final products. .When from 



?, 



neutral germinal material of an insect egg 



w **,., is produced a male or female creature, or a 

 tr i/ worker or soldier (as this or that influence acts), 



Jr JM . 



XjyXf /.the process is no other, and presents no greater 



fir ( Difficulties, than when an experimenter, taking the 



J/voung bud of a plant, according to the conditions 



* yA\io which he subjects it, can turn it into a vegeta- 



W ^j/fcive or into a reproductive shoot, a thorn or a root ; 



^ J* tio different to what occurs when the investigator, 



L/cutting into a Cerianthus, produces a second or 



})(* third mouth, surrounded by tentacles, or in the 



J/p case of Clone surrounded by eye-spots. 



tf'f '$ \ ^ ^ as t> een shown, I think, in these pages that 

 n 4f^' Vmuch of what Weismann would explain by deter- ijf 

 ^ niinants within the egg must have ^^^^ ^nfcirio / / 



