336 WHEELER— ANT LARV^. 



spring, I would reply that from a general biological point of view 

 the resemblances between the two cases are still fundamental and 

 suggestive. This has been shown by Giard in one of his interesting 

 papers (1905, 1911). He says: 



Comparative ethology permits us to go further and shows us in the 

 clearest manner that the relations between the parent organism and its prog- 

 eny are in principle absolutely the same as those which exist between a 

 parasitized animal and its parasite and that after a period of unstable equi- 

 Hbrium, in which one or the other of the two organisms in contact finds 

 itself injured to the profit of its associate, there is a tendency to establish a 

 definitive status of mutual equilibrium in which the two partners find in their 

 association an advantage in the struggle against the ensemble of common 

 causes of destruction, both cosmic and bionomic. 



A partial attainment of the equilibrium mentioned by Giard, both 

 in the nursing relation of ants and that of sanguinea to Lomechusa 

 is brought about by mutual feeding. In neither case is the exchange 

 of food between the two parties quantitatively equal, but the exu- • 

 dates as stimuli, in all probability make up in quality or intensity for 

 what they lack in quantity. 



This brings us back to Wasmann's amical selection which still 

 remains to be considered. It has often been remarked that the 

 symphiles are strangely like our domestic animals in that they live 

 in a social environment where they are protected from enemies and 

 abundantly fed. In the case of the domestic animals Darwin long 

 ago showed that such an environment favors the production of ex- 

 traordinary variations, and Pearson (1897) and Trotter (1916) 

 agree that when organisms unite to form larger biological units such 

 as the Metazoan body, herds, colonies and societies, the individuals 

 though necessarily limited in their evolution along particular lines 

 nevertheless in other respects escape from the stabilizing influence of 

 natural selection and exhibit unusual freedom of development and 

 specialization. Both the domestic animals and the symphiles which 

 really become integral members of the insect societies in which they 

 are permitted to live, show this freedom in the development of un- 

 usual structural and color characters, as we see in albinos, peculiar 

 breeds of fowl, pigeons and dogs, Paussids and Clavigerids with 

 monstrous antenn?e, ant-chalcids like Kapala and Isouicralia, with 

 huge thoracic spines, etc. Similar phenomena are common in many 



