The Origin of the Markings of Caterpillars. 329 



than that of making the insects conspicuous ? 

 Had we to deal with sexually mature forms, we 

 should, in the first place, think of the action of 

 sexual selection, and should regard these spots as 

 objects of taste, like the ocelli on the feathers of 

 the peacock and argus-pheasant. But we are 

 here concerned with larvae, and sexual selection 

 is thus excluded. 



The eye-spots must therefore possess some 

 other significance, or else they are of no import- 

 ance at all to the life of the insect, and are purely 

 " morphological characters ; " in which case, sup- 

 posing this could be proved, they would owe their 

 existence exclusively to forces innate in the organ- 

 ism itself a view which very closely approaches 

 the admission of a phyletic vital force. 



I am of opinion, however, that eye-spots certainly 

 possess a biological value as a means of terrifying 

 they belong to that numerous class of characters 

 which occur in the most diverse groups of animals, 

 and which serve the purpose of making their 

 possessors appear as alarming as possible. 



The caterpillars of the Sphingidcz are known 

 to behave themselves in different manners when 

 attacked. Some species, such, for instance, as 

 Sphinx Ligustri and Smerinthus Ocellat^(,s y on the 

 approach of danger assume the so-called Sphinx 

 attitude ; if they are then actually seized, they dash 

 themselves madly to right and left, by this means 

 not only attempting to get free, but also to terrify 



