1876 .] Notices of Books. 403 
suspicion of the fallacies involved in the argument and the 
illustration. It is assumed that the outward circumstances 
remain the same ; that young animals are exactly intermediate 
between their parents, and, above all, that the advantage of the 
improved “ sport ” over the average individual is as two to one. 
Now let us, in turn, suppose that an animal is produced swifter 
than the rest of its species; that an enemy makes its appearance 
swifter than the average individual, but slower than the “ sport.” 
The chance of the latter surviving and leaving progeny would 
then not be double that of the ordinary individual, but greater 
beyond all comparison. Its mate would probably not be one of 
the slowest of the species, since all such would stand the 
greatest chance of being devoured by the enemy. Amongst its 
offspring, judging from fadts daily observed, there would be 
some as swift as itself, and possibly even swifter, and these 
would become the progenitors of the new race. Or let us take 
the “North British Reviewer’s” illustration of a white man 
shipwrecked upon an island inhabited by blacks, and there 
intermarrying with a native woman. Among his children, 
despite the dodtrine of averages which bids a poor wretch 
shivering over an empty fire-grate on a cold winter’s night to 
feel comfort in the thoughts of a great conflagration at the other 
end of the street — some will be found very closely resembling 
their father. If now a new disease fatal to blacks and com- 
paratively harmless to whites, like the measles at Fiji, appears 
and becomes endemic in the island, the children of “ our ship- 
wrecked hero ” would escape its ravages just in proportion as 
they inherited their father’s constitution, and the population of 
the island might in such a case become permanently a light 
yellow. 
On the fertility of hybrids Mr. Maclaren remarks : — “ Both 
Lamarck and our author are obliged to allow the general 
existence of a great degree of sterility among hybrids, and 
though they may give some instances of partial fertility, we are 
strongly reminded of the old canon, exception proves the rule.” 
This “ old canon ” is in the eyes of men of science about as 
acceptable as the saying of Sir Thomas Browne — I believe, 
because it is impossible.” Suppose it were found that the law 
of definite proportions did not extend to all the elementary 
bodies, would any chemist contend that such an exception 
“ proved the rule ? ” So far from it, he would cease to regard 
the law above-mentioned as a “ rule ” at all, and consider it 
merely as a provisional and imperfedt generalisation. Leaving 
on one side the case of the leporides, the cross between the hare 
and the rabbit (whose existence Mr. Maclaren does not think 
proper to admit), there are cases quite sufficient of fertile hybrids 
amongst the respective groups of finches, of grouse, and of 
ducks. So that, though as Prof. Oscar Schmidt happily says, 
“ by ill-luck ” the most ancient and common case of hybridisa- 
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