1875.] Difficulties of Darwinism. 333 
encountered as regards the production of poison and of 
textile matter. 
There is a strange phenomenon known as Melanism. In 
the more southern portions of the globe animal forms have 
a striking disposition to assume a black colour. ‘This 
tendency is well marked in the temperate latitudes of South 
America, in South Africa and Madagascar, in Australia, 
New Zealand, and New Guinea, where it reaches the 
Equator. Perhaps the most familiar instance that could be 
cited is the black swan of Australia. New Zealand has a 
black parrot, and the high latitudes of South America a 
black humming-bird. Among inseéts it is well known that 
few large groups display a more brilliant general colouration 
than the Cetoniadez, or rose-beetles, which have been not 
inaptly characterised as walking jewels. Yet in South 
Africa and Madagascar, where they are richly developed, 
they, too, appear in mourning. The genera Stenotarsia, 
Liostraca, Heteroclita, Callipechis, Rhinoceta, Xiphoscelis, and 
not a few others that might be mentioned, have scarcely a 
species which is not in great part black. Why this should 
be the case—while groups which elsewhere affect light or 
brilliant colours should be represented in the regions just 
mentioned by black members—is an unsolved question. 
Peculiarity of climate or of soil is out of the question, 
since the countries in which Melanism has_ been 
recognised include every conceivable variety of both, and 
since they form in these respects no exception to the 
remainder of the habitable globe. Can Natural Sele¢tion be 
the cause? Take the case of a black swan. Will his 
opportunities of surviving in the struggle for existence, and 
of leaving posterity behind him, be greater than if he had 
been white, like the swans of the northern hemisphere ? 
We see no reason why this should be the case. But 
supposing, for argument’s sake, that the black swan has the 
advantage, it might then be asked why he had not also been 
produced and perpetuated in other regions where swans 
occur. We want to find the law which connects the black 
Swan with Australia, in preference to any other region of 
the world, and so far, Evolution leaves us as much in the 
dark as the old doctrine of distin¢t and special creation. 
But Melanism is only one single instance of a general 
principle. Almost every country sufficiently large and suffi- 
ciently rich in animal and vegetable species, has its local 
characteristics. Place a miscellaneous, but local, assort- 
ment of insects before an experienced entomologist, and, 
though he may know nothing of them, and have never seen 
