ANALOGICAL BESEMBLANCBS. 445 



Several equally striking cases of imitation in the Lepidop- 

 tera of the Malay Archipelago and Africa, and with some 

 other insects. Mr. Wallace has also detected one such caSe 

 with birds, but we have none with the larger quadrupeds. 

 The much greater frequency of imitation with insects than 

 with other animals, is probably the consequence of their 

 small size; insects cannot defend themselves, excepting in- 

 deed the kinds furnished with a sting, and I have never 

 heard of an instance of such kinds mocking other insects, 

 though they are mocked; insects cannot easily escape by 

 flight from the larger animals which prey on them; there- 

 fore, speaking metaphorically, they are reduced, like most 

 weak creatures, to trickery and dissimulation. 



It should be observed that the process of imitation prob- 

 ably never commenced between forms widely dissimilar in 

 color. But, starting with species already somewhat like each 

 other, the closest resemblance, if beneficial, could readily be 

 gained by the above means, and if the imitated form was 

 subsequently and gradually modified through any agency, 

 the imitating form would be led along the same track, and 

 thus be altered to almost any extent, so that it might ulti- 

 mately assume an appearance or coloring wholly unlike 

 that of the other members of the family to which it be- 

 longed. There is, however, some difficulty on this head, 

 for it is necessary to suppose in some cases that ancient 

 members belonging to several distinct groups, before they 

 had diverged to their present extent, accidentally resem- 

 bled a member of another and protected group in a suffi- 

 cient degree to afEord some slight protection, this having 

 given the basis for the subsequent acquisition of the most 

 perfect resemblance. 



ON" THE NATURE OE THE AFFINITIES CONNECTING 

 ORGANIC BEINGS. 



As the modified descendants of dominant species, belong- 

 ing to the larger genera, tend to inherit the advantages 

 which made -the groups to which they belong large and 

 their parents dominant, they are almost sure to spread 

 widely, and to seize on more and more places in the 

 economy of nature. The larger and more dominant 

 groups within each class thus tend to go on increasing in 



