316 



THE AMEBIC AX XATURALIST 



[Vol. LIV 



be willing to do so. This objection is readily met by ex- 

 perimental evidence, for every entomologist is fully 

 aware of the fact that it is ordinarily quite impossible to 

 rear insects of restricted food habits upon other than 

 their normal food-plants. It is true that an acceptable 

 plant may sometimes be found by those familiar with the 

 vagaries of related species of insects, but in such cases 

 we may safely assume that the experimentally selected 

 plant may later prove, in at least some cases, to be one 

 sometimes picked out for food in nature. 3 It would be 

 an unwarranted assumption, therefore, to suppose that 

 the maternal instinct of oviposition does not at the pres- 

 ent time represent fairly well the tastes of the larva. We 

 may reasonably ask, however, whether the selection of 

 the mother may not have impressed itself upon the larva 

 after continual repetition or whether the taste acquired 

 by the continual feeding of the larva may not persist 

 into the adult, just as fondness for sweets may become a 

 lifelong attribute in examples of the human species pam- 

 pered in youth by indulgent mothers. During the prog- 

 ress of evolution as food-habits have become fixed, it is 

 evident that any changing tastes on the part of the larva 

 must have become a part of the egg-laying instincts of 

 the mother, through the action of natural selection or 

 otherwise, before any change of food-plants could occur. 

 On the other hand, any change in the instincts of oviposi- 

 tion, not incompatible with larval tastes, might quickly 

 become a definite characteristic of the species. If any 

 adults should select unsuitable plants their progeny 

 would quickly perish. The maintenance of definite pref- 

 erences can thus be seen to be readily perpetuated 

 through the action of natural selection in the survival of 

 the fittest strains and the elimination of the unfit ones. 

 It will be evident later, however, that subsistence on 

 many food-plants would appear to have originated after 



,hi,-L„.'.|. Cn.stnnn) J, uhi.h th.-y ,lo nut normally fee,!, but which are 

 acceptable to many larva, in the absence of their natural food-plant. 



