46 MIMICRY, AND OTHER PROTECTIVE 
propounded by MacLeay, and developed by Swainson, 
with an amount of knowledge and ingenuity that 
have rarely been surpassed. This theory was emi- 
nently attractive, both from its symmetry and com-- 
pletengss, and from the interesting nature of the 
varied analogies and affinities which it brought to 
light and made use of. The series of Natural His- 
tory volumes in “Lardner’s Cabinet Cyclopedia,” 
in which Mr. Swainson developed it in most de- 
partments of the animal kingdom, made it widely 
known; and in fact for a long time these were 
the best and almost the only popular text-books for 
the rising generation of naturalists. It was favour- 
ably received too by the older school, which was 
perhaps rather an indication of its unsoundness. A 
considerable number of well-known naturalists either - 
spoke approvingly of it, or advocated similar princi- 
ples, and for a good many years it was decidedly 
in the ascendent. With such a favourable introduc- 
tion, and with such talented exponents, it must have 
become established if it had had any germ of truth 
in it; yet it quite died out in a few short years, 
its very existence is now a matter of history; and so 
rapid was its fall that its talented creator, Swainson, 
perhaps lived to be the last man who believed in it. 
Such is the course of a false theory. That of a 
true one is very different, as may be well seen by 
the progress of opinion on the subject of Natural 
Selection. In less than eight years “‘The Origin of 
Species” has produced conviction in the minds of 
