404 Notices of Books - [July, 
tion — that of the mule and the hinny — supports the common 
doctrine, all that we can truthfully say is that some hybrids are 
fertile, whilst others are not, which is simply no rule at all. 
This subject is one which stands in need of extended and 
careful experimental research. Only we fear that some one of 
the “ societies ” which have taken the morals of the English 
public under their especial care will some day suddenly awake 
to the conclusion that such experiments are “immoral, 
degrading, and deceptive,” and will frighten a weak-minded 
legislature into passing an “Anti-hybridisation Act” for the 
further restraint of scientific curiosity. 
As may well be imagined, our author has found in the course 
of his reading many difficulties which lie in the way of a full 
acceptance of the Darwinian theory. Nor is he much better 
satisfied with rival hypotheses. He pronounces that of Prof. 
Owen very vague, and that of Prof. Mivart “ not very in- 
telligible ” — a perfectly just conclusion. The Duke of Argyle, 
he holds, leads us “ at once out of the realm of science into that 
of miracle.” 
The fact remains that the question of the origin of species is 
yet very far from solution. Most working naturalists believe in 
evolution, and phenomena which scarcely admit of any other 
explanation, meet us on every hand. But as Sir C. Lyell and 
Mr. Darwin grant, of the laws of such evolution we are still 
profoundly ignorant. Yet these we must endeavour to ascertain 
before we can with any confidence hope to discover how it is 
brought about. Surely this task may be best accomplished by 
applying such theories as that of Darwin to the phenomena w 7 e 
observe, noting what they explain and where they fail, and 
modifying our hypotheses accordingly. Here, as might be 
expected, Mr. Maclaren takes leave of his readers. After 
collecting the evidence on both sides, so far at least as it is 
presentable in words, and intelligible to one who is not a 
biologist, he rejects Darwin ; he does not accept Mivart, and 
thinking the mystery of the origin of species unexplained, he 
can give no hint towards its solution. We should counsel the 
young naturalist neither to reject nor yet to accept Darwinism, 
but to use it tentatively and provisionally. 
One feature in Mr. Maclaren’s work we have great pleasure in 
noticing. He writes as a scholar and a gentleman. Nowhere 
does he impute dishonourable motives, and nowhere does he 
appeal to the odium theologicum. Where he finds his autho- 
rities using this assassin’s weapon he leaves them. 
