INSTINCTS ARISE BY SELECTION 163 



We find that by the study of nine wasps of an American 

 species, A. urnaria, of the very genus Ammophila, which, 

 as previously described, chiefly furnished the basis of 

 speculation, the American naturalists have shown that 

 the immense superstructure is in large part due to a fertile 

 imagination. So far from the assumed perfection and 

 accuracy with which every detail is supposed to be 

 repeated, the instinct is shown to be excessively variable. 

 The frequently-quoted conclusions that the object of the 

 sting is to reduce the larvae to helplessness and yet keep 

 it in a fresh condition, that a dead larva would be unsuit- 

 able food and an active one a danger to the offspring of 

 the wasp — all these conclusions are entirely disposed 

 of by a few careful specially directed observations. These 

 show that the larva rapidly dies in a large proportion 

 of cases and yet affords excellent food, and that it may 

 remain sufficiently uninjured to wriggle continuously 

 without stimulation, and to move violently when bitten 

 by the larva of the wasp. 1 



The following activities or performances are regarded 

 as truly instinctive, viz. as due to the compulsion of heredi- 

 tary nervous mechanism : — Stinging, the methods of attack, 

 capture and carriage of prey peculiar to each species, the 

 kind of prey selected, the general style and situation 

 of the nest, the form of cocoon. 2 



The American naturalists finally conclude their volume 

 with these words : — ' The general impression that remains 

 with us as a result of our study of these activities is that 

 their complexity and perfection have been greatly over- 

 estimated. We have found them in all stages of develop- 

 ment and are convinced that they have passed through 

 many degrees, from the simple to the complex, by the 

 action of natural selection. Indeed, we find in them 

 beautiful examples of the survival of the fittest.' 3 



As long ago as 1889 the present writer had argued 

 that the Lamarckian interpretation of the instincts of 

 Ammophila or Sphex introduced the same difficulty as 



1 Instincts and Habits of Solitary Wasps, pp. 30, 31. - I.e. p. 234. 

 3 See the review of Dr. and Mrs. Peckham's work in Nature, vol. lix, 

 1899, pp. 466-8. 



M 2 



