167 
and distorted the wings may become in such exertions, I have never 
known a fracture of nervures or membrane to result, the organs 
resuming their natural position even after having been bent double 
for some hours. While entomologising in Natal, my Kafir collector 
used often to bring me numerous examples of the commonest species 
in his box, and when engaged in the necessary work of rejection, 
I constantly found the limp-winged Danaidae and Acraeidse, as soon 
as they were released from the transfixing pin, fly off with perfect 
ease and apparent nonchalance. . . . This elasticity of structure 
is not confined to the butterflies in question, being a character of 
many moths, and markedly of some belonging to the families 
Agaristidae and Zygaenidae. It is remarkable that the three South- 
African moths in which I have found this peculiarity most developed, 
viz., Pais decora, Eusemia euphemia, and Glaucopis formosa—all 
have a strong and offensive odour, emit drops of white or yellow 
fluid, and are slow-flying, brightly coloured, and abundant species.”— 
(R. Trimen. On “Mimetic Analogies among African Butterflies.” 
Trans. Linn can Soc. vol. xxvi., pp. 498-499.) 
In the second place the action of Natural Selection 
must be in inverse ratio to the amount of the direct action 
of changed conditions by virtue of which similar organisms 
are influenced by similar conditions in a similar manner. 
In this case there is either no need for Natural Selection at 
all ; or it plays at most a comparatively insignificant part 
in the transformation. 
Now, it is worthy of observation that it was in this par 
ticular connection that Mr. Darwin makes a very notable 
admission, in a letter dated October 13th, 1876:— 
“ In my opinion, the greatest error I have committed has been 
not allowing sufficient weight to the direct action of the environ 
ment, i.e., food, climate, etc., independently of Natural Selection. 
. . . When I wrote my ‘ Origin,’ and for some years afterwards, 
I could find little good evidence of the direct action of the 
environment; now there is a large body of evidence, and your 
case of the Saturnia is one of the most remarkable of which I 
have heard.”—(Life and Letters, vol. Hi., p. 158.) 
But not only is this a sphere in which the direct trans 
forming influence of the environment is made obvious,— 
it is clear that there are many cases in which the process