LECTURES, a7 
individual its life, so they would not be transmitted to descendants. It 
is only the useful variations that can be handed down. 
Under domestication, where there is no fear of enemies, rapid 
changes occur at once ; for instance, how a litter of pups will vary 
in colour! 
I remember once keeping a pair of ordinary brown rabbits in a 
wire enclosure where they could burrow freely. They bred there, but 
after a time became a nuisance, as they turned up in the middle of 
the tennis court one morning, so we dug them out and found fifteen 
youngsters varying in colour from fawn to black. 
You all know how rare white animals are in nature, and how 
common they are under domestication. The fact is that white 
varieties are constantly apt to occur, but in the natural state, their 
conspicuousness at once marks them as a prey to their foes. 
The present colours of wild animals, then, are the result of long 
selection. We see how beautifully they are adapted to their 
surroundings. The rabbit in the fern is brown, the snipe and wood- 
cock among dead leaves and broken sticks are mottled, while the 
grass-hopper is bright green. Most Arctic animals are white. Here 
selection favours the white variety. The polar bear needs his white 
coat to conceal himself from his victim, while the Ptarmigan and Arctic 
hare escape observation and capture in the same way. Even the 
exceptions prove the rule. The sable with his glossy brown coat 
hardly ever trusts himself out of trees, and the raven only seeks 
carrion, and is strong enough not to mind if his sombre hue attracts 
notice. 
All animals that live in the desert, the lion as well as the antelope, 
are sand coloured. 
We will look a little closer into one case of protective colouring, 
that of Birds’ Eggs. They are made of chalk, and chalk we know is 
white, so the original birds’ eggs were no doubt white too, just as those 
of crocodiles and lizards are to this day. But white is very conspic- 
uous, and so a bird that happened to lay slightly coloured eggs would 
be more likely to save them from hawk or crow or predatory animal, 
and rear them successfully. The peculiarity would be transmitted 
just as a long nose with us, and so eggs would gradually become 
coloured. 
What are the facts we observe now? Birds that build in holes—. 
the sand-martin, king-fisher, and wren have still white, or almost 
white eggs. Those that lay in open nests on the ground—the plover, 
snipe and curlew have eggs so like the rough grass among which they 
