RETIE WS. 
69 
arising accidentally and perpetuated ; secondly, he attacks many of the 
remarkable instances of so-called instinct, and destroys much of their force. 
As regards the supposition that instinct is inherited habit, there seems every 
reason to think that Mr. Darwin’s view is the correct one. It is impossible 
for the physical philosopher to deny that every organism has the power of 
calling into play, or allowing to fall into disuse, any one of the greater number 
of its parts or faculties, and it is equally impossible to deny the truth of the 
proposition that such parts as are thus called into action descend to future 
generations. Now, since even in the case of mental impulses, each action of 
the brain must be accompanied by a corresponding change of substance, it is 
clear that in this way accidental variations of mental operation may be rendered 
permanent, and thus allowed to descend from one generation to another. 
We may therefore in this manner account for many of the most puzzling 
examples of instinct. And when we remember that animals under domesti- 
cation lose most of their wild instincts and acquire a new series as the result 
of artificial selection , the analogy between the effects of natural selection 
and instinct on bodily structure ceases to be a difficult one. 
Having analysed very fully the nature of instinctive actions, Mr. Darwin 
proceeds to show that the instinct of the bee to form wax from flowers is by 
no means a perfect one, for these insects will prepare the comb from various 
artificial substances, such as 11 wax hardened with vermilion and softened 
with lard,” “a cement of wax and turpentine,” “ oatmeal,” &c., &c. He 
then makes the following remarks on the nature of the cuckoo’s instinct : 
“With respect to the last point insisted on, namely, of the young 
European cuckoo ejecting its foster-brothers, it must first be remarked 
that Mr. Gould, who has paid particular attention to this subject, is con- 
vinced that the belief is an error ; he asserts that the young foster-birds are 
generally ejected during the first three days, when the young cuckoo exerts 
by its hunger-cries, or by some other means, such a fascination over its 
foster-parents, that it alone receives food, so that the others are starved to 
death, and are then thrown out, like the egg-shells or the excrement, by the 
old birds.” 
We heartily wish we had space to make further quotations from this admir- 
able volume ; but since we must leave the book for the present, we would 
earnestly urge all our readers, whether naturalists or not, to take it up and 
read it carefully. There is not a trace of special pleading in the whole 
argument from beginning to end ; it is an able and honest exposition of facts 
and of the inductions naturally formed upon them. It is the work of one 
of the most accurate and experienced observers of the age, and cannot fail 
to enlighten even those whom it cannot convince. 
ELECTRICITY FOR STUDENTS.* 
T\R. NO AD, the well-known author of a Manual of Electricity, now pre- 
U sents the student with a closely-printed volume of more than five 
hundred pages on the same subject. It is a most elaborate compilation of 
* “ The Student’s Textbook of Electricity.” By Henry M. Noad, Pli. D. 
E.R.S. F.C.S. Lecturer on Chemistry at St. George’s Hospital. With four 
hundred illustrations. London : Lockwood and Co. 1807. 
g 2 
