Review.



93



REVIEW.


VIGOUR AND HEREDITY.*


In commenting upon this extremely interesting book, we can

only touch upon certain points and theories which are especially

connected with aviculture, although probably many of our members

will peruse the chapters dealing with mammals with equal zest.

The theory that has in part brought Mr. Bonhote’s book into being

is, having regard to birds, that their song, their colouring, their

fertility in reproduction, etc. is due to “ vigour,” and that fluctuations

of this inward force are caused by environment, of which the main

factors are temperature, humidity, and food. The writer claims that

the general colouration of mammals and birds throughout the world

is governed by these factors.


In this one cannot altogether agree. Surely changes in colour¬

ation in summer and winter are greatly due to outward surroundings

for causes of concealment. Is the Snowy owl or the Iceland falcon

less vigorous than the raven, and do not the two former assume

white to conceal themselves from their prey, which, as in the case

of the ptarmigan or the hare, also happens in order to be less visible

to the enemy; whilst the raven, a carrion-feeder and not preyed

upon, finds no need to change his black coat. The British king¬

fisher, although finding his food with difficulty in a hard winter, has

not yet become less tropical in colouring, although for many genera¬

tions his kind would frequently suffer more privations than let us

say, the common sparrow, and therefore decline in vigour. And is

colouring “ largely an index of vigour,” and not more chiefly for

protection from enemies and for asthetic objects? We can under¬

stand that through loss of vigour there follows a loss of colouring,

but we feel that the colouring, although the result of vigour, has

FOE ITS FINAL' OBJECT something beyond that.


We take as examples the females of pheasants and ducks,

w T hose colouring closely resembles the surroundings when on their

nests ; and the gorgeous colouring of the males, as in the golden



* Vigour and Heredity, by J. LEWIS BONHOTE, M.A., F.L.S., F.Z.S.,

with coloured and uncoloured plates, and diagrams in text, price 10/6.


London. WEST, NEWMAN & Co., 54, Hatton Garden. 1915.



