PLAY AND INSTINCT. 59 



satisfy their hunger, and when Wasman placed a dead 

 pupa actually in their jaws, they made no attempt to eat 

 it, only licked it inquiringly, and left it. But as soon as 

 one of their slaves — that is, a worker of the Formica 

 fiisca — was introduced, they approached and begged it 

 for food. The slave hastened to the honey drop, filled 

 her mouth, and brought the food to her ladyship." * 

 AYhat a splendid example this would be of the hereditary 

 effect of disuse, says Weismann, if only these workers 

 were not sterile! As the unreasoning conduct of these 

 workers excludes the idea that their behaviour springs 

 from the judgment of individuals, there remains for an 

 explanation only selection, and selection of the mother 

 at that. It must be noted, on the one hand, that those 

 ant communities are more thriving whose productive 

 females bring forth workers whose individual varia- 

 tions are in the direction of the decided modifications in 

 physical qualities and in instinct mentioned above, f On 

 the other hand, if the force of selection relaxes with 

 reference to the weakening instinct, there results a 

 community where the fruitful females produce workers 

 whose instinct for collecting, rearing the young, and 

 foraging is constantly diminishing (negative selection or 

 panmixia). 



Instances like this must increase the doubt about 

 the inheritance of acquired characteristics. Let us now 

 turn our attention to some other arguments for neo- 

 Darwinism. To its advocates the fact is very significant 

 that not a single example seriously threatening Weis- 

 mann's theory has been brought forward by their op- 



* Weismann, Der Allraacht der Naturzuchtung, Jena, 1893, 

 p. 52. 



f The same idea may be found in Darwin's Origin of Species, 

 in loc. 



