could explain that law so well as a few simple words of the great 

 naturalist himself, and which I will quote : " Nature •» ^ * * 

 cares nothing lor appearances, except in so far as they are useful 

 to any being. She can act on every internal organ — on 

 every shade of constitutional difference — on the whole machinery 

 of life. Man selects only for his own good — Nature only for 

 that of the being which she tends. * *^ * * Under nature, 

 the slightest differences of structure or constitution may well 

 turn the nicely-balanced scale in the struggle for life, and so be 

 preserved." 



The more closely an animal resembles its surroundings in form 

 and colour so much the more easily can it elude its pursuer, and 

 also escape detection when approaching its own prey. Take for 

 example those moths whose wings are coloured and veined like the 

 fallen leaves on which they lie motionless, or the hunting spiders 

 which mimic flower buds, or the large caterpillars which resemble 

 poisonous snakes. Or the sand-coloured insects of the desert 

 which according to Grant Allen "have become sand-coloured 

 because the least sandy were perpetually picked out for destruction 

 by their ever watchful foes, while the most sandy escaped and 

 multiplied. In the desert, a black, white, or red insect would be 

 immediately detected and devoured by its natural enemies the birds 

 and lizards. But any yellowish insects would be less likely to attract 

 attention at first sight, and would be overlooked as long as there 

 were any more conspicuous individuals. So that in a short time 

 the desert would be depopulated of all but the yellowest insects, 

 which would survive and become the parents of future generations," 



In conformity with this law which is in reality a ' ' ceaseless 

 struggle for food and for life," we find that most animals are pro- 

 tectively coloured, except those which are so constituted as to need 

 no such protection. This law of mimicry has been investigated by 

 many of nature's lovers since first its existence was demonstrated 

 by Darwin. Within the last few months most interesting observations 

 in connection with it have been published by Professor Drummond 

 in his fascinating work on " Tropical Africa." I cannot do better 

 than give you one or two of his most striking illustrations in the 

 brief space of time that is allotted me this evening. 



Professor Drummond's opinion is that mimicry serves not only 

 as a natural method of protection, but also as warning. For 

 instance, many of the most brilliantly coloured tropical butterflies 

 are inedible owing to the presence in their bodies of acrid juices. 

 Their gorgeous hues are thus hung out as danger signals to their 

 natural enemies, the birds, monkeys, and lizards, which having' 

 once feasted upon similar insects have no wish to repeat the ex- 

 periment. " The same rule," he adds, " applies to all bees^ 



