132 THE MALAYAN PAPILIONIDE AS 
members exhibit no appreciable change. The wings 
of Butterflies, as Mr. Bates has well put it, “serve 
as a tablet on which Nature writes the story of the 
modifications of species;” they enable us to perceive 
changes that would otherwise be uncertain and diffi- 
cult of observation, and exhibit to us on an enlarged 
scale the effects of the climatal and other physical 
conditions which influence more or less profoundly 
the organization of every living thing. 
A proof that this greater sensibility to modifying 
causes is not imaginary may, I think, be drawn from 
the consideration, that while the Lepidoptera as a 
whole are of all insects the least essentially varied in 
form, structure, or habits, yet in the number of their 
specific forms they are not much inferior to those 
orders which range over a much wider field of nature, 
and exhibit more deeply seated structural modifica- 
tions. The Lepidoptera are all vegetable-feeders in 
their larva-state, and suckers of juices or other liquids 
in their perfect form. In their most widely separated 
groups they differ but little from a common type, 
and offer comparatively unimportant modifications of 
structure or of habits. The Coleoptera, the Diptera, 
or the Hymenoptera, on the other hand, present far 
greater and more essential variations. In either of 
these orders we have both vegetable and animal- 
feeders, aquatic, and terrestrial, and parasitic groups. 
Whole families are devoted to special departments in 
the economy of nature. Seeds, fruits, bones, car- 
cases, excrement, bark, have each their special and 
