REVIEWS--ON THE ORIGIN OF SPECIES. 381 
proportion to those which have become extinct, I can see no very great difficulty 
(not more than in the case of many other structures) in believing that natural 
selection has converted the simple apparatus of an optic nerve merely coated 
with pigment and invested by transparent membrane, into an optical instrument 
as perfect as is possessed by any member of the great Articulate class. 
He who will go thus far, if he finds on finishing this treatise that large bodies 
of facts, otherwise inexplicable, can be explained by the theory of descent, ought 
not to hesitate to go further, and to admit that a structure even as perfect as 
the eye of an eagle might be formed by natural selection, although in this case he 
does not know any of the transitional grades. His reason ought to conquer his 
imagination, though I have felt the difficulty far too keenly to be surprised at any 
degree of hesitation in extending the principle of natural selection to such start- 
ling lengths.” 
An entire chapter, and a most instructive one, in Mr. Darwin’s 
book, is devoted to the subject of Instinct, another serious obstacle 
as all will readily understand, to the reception of the transmutation 
theory. Mr. Darwin seeks to overcome this obstacle, by establishing 
two points : first, that a certain amount of judgment or reason enters 
into the composition of instinct; and secondly, and chiefly, that, 
instinct can be shewn, in certain remarkable cases, to be a quality of 
gradation, so to say. In the ceil-building instinct of the bees for 
- example, he traces out, as he imagines, a specific connexion between 
the humble bees and the hive bee—the Mexican Melipoma domestica 
affording a transition-link. But here, we should consider, that, the 
principle of instinct is perhaps in no case a simple specific principle, 
nor even a generic one; but a principle pervading entire families or 
groups, and, as such, one that we might naturally infer to offer 
inherent degrees of variation. To establish the point aimed at by 
Mr. Darwin, we ought to be able to shew, that the humble-bee 
could be made to acquire the higher artistic-instinct of the hive-bee. 
We may be told that this might probably be effected under favour- 
able circumstances, and with sufficient lapse of time; but as this 
assumption is altogether without proof, we have an equal right to 
infer that these separate amounts, or rather kinds of instinct, were 
originally bestowed on these different bees at their special creation, 
The followers of Mr. Darwin’s theory, would, of course, ridicule the 
idea of a separate creation on the part of insects so nearly allied; but 
as they can offer us nothing to the contrary but inferences and 
surmises, every one is at liberty, on this point, to entertain his own 
pinion. Instinct may be legitimately regarded as entirely depend- 
