NATURAL SELECTION SINCE DARWIN 85 



mal. Kellogg draws the same conclusion from his 

 observations on insects : 



"In my own eyes has for long stood the fa- 

 miliar case of the mimicry of our common American 

 monarch butterfly (Anosia plexippus), by the vice-J^- 

 roy butterfly (Basilarchia archippus) . . . . Ano- 

 sia is distasteful to birds; after a few experiments 

 with Anosia a bird recognising this ill-tasting morsel 

 . . . leaves the monarchs alone. Not only mon- 

 archs, however, but also viceroys which are to all 

 external seeming only slightly smaller monarchs." 3 



Both butterflies belong to groups whose typical rep- 

 resentatives have nothing in common as far as mark- 

 ing and colouring are concerned; of all Basilarchia, 

 the viceroy alone resembles Anosia, and one may sup- 

 pose that this resemblance is constantly fostered by 

 selection. 



"But of what avail for this purpose of deceit was 

 the first tiny tinge or fleck of red-brown on the star- 

 ing black and white wings of the ancestral viceroy?" 

 Kellogg asks. 



Many similar examples could be brought forward; 

 natural selection seems to regulate in a vague way ex- 

 isting variations rather than to create or develop any 

 new ones. 



The usefulness of a character seems, after all, to be 

 limited to a certain degree of its development. Be- 



3 V. L. Kellogg. Darwinism To-day, pp. 49-50. 



