APRIL 14, 1904] 
NATURE 
555 
termination and in domestication. \We are reminded 
that the nineteenth century, so progressive for zoology, 
is responsible for many sad exterminations, in some of 
which man has played a careless part. The possibili- 
ties of adding to the list of domesticated animals are 
discussed, but the result of this interesting inquiry is 
not encouraging : it may be that the elephant and zebra 
will yield to domestication in Africa; the number of 
herbivores capable of acclimatisation in parks can be 
greatly increased, but the secret of domestication seems 
to have been lost as civilisation was gained, and no 
new additions of importance can be looked for with 
any confidence. It almost seems as if our ancient 
forbears had exhausted the possibilities. This 
naturally leads to a discussion of the origin of domesti- 
cated mammals, in the course of which it is confessed 
that we are unable to point to the ancestral stock of 
the sheep, and that there is great uncertainty in regard 
to the horse. The breeds of goats seem to be derived 
from the Persian pasang, the donkey seems referable 
to a Somaliland wild ass, and it is maintained, perhaps 
toc dogmatically, that the numerous breeds of domesti- 
cated cattle in Europe all trace their ancestry to the 
great extinct wild ox, or aurochs. The difficult 
problem of extermination recurs in an essay on ‘“* A 
Land of Skeletons’’—Argentina, once the head- 
quarters of glyptodons, mylodons, megalotheres, and 
other splendid giants, which died off one after another 
through the long ages during which the mud of the 
Pampa was accumulating. Here man cannot have 
been the eliminating factor, but what the ‘‘ death- 
bringing shackles ’’ were we do not know. 
For another group of essays the key-word is distri- 
bution. The marked individuality of the fauna of 
Celebes, the possibility of a previous land-connection 
between South America and Australasia, the character- 
istics of the African fauna, the inhabitants of deserts, 
are among the subjects discussed. Opportunity is 
found to correct the still lingering belief that deserts 
are uninterrupted plains of smooth sand, originally 
deposited at the bottom of the sea, from which they 
have been raised at a comparatively recent epoch. 
“Tt may be laid down as a general rule that the 
greater the amount of sand to be found in a desert, 
and the greater the difference between the animals in- 
habiting that desert from those dwelling in the adjacent 
districts, the greater will be the antiquity of the 
desert itself. In the case of a desert forming a com- 
plete barrier across a continent, like the Sahara, if 
the animals on one side are quite different from those 
on the other, its antiquity will be conclusively demon- 
strated.” 
In another group of essays we have illustrations of 
the light which past history sheds upon the present. 
Thus Mr. Lydekker discusses some extinct Argentine 
mammals, such as the ‘“ ground-sloths,’’ some of 
which ‘‘ appear to have been kept in caves as domesti- 
cated animals by the ancient inhabitants of Pata- 
gonia’’ (!); the armour-clad whales, such as Zeu- 
glodon, the characters of which point to an affinity 
between toothed whales and carnivores; the ancient 
hippopotamuses; and the prehistoric cats and dogs. 
Coloration is the key-note of another group of 
NO. 1798, VOL. 69] 
essays. Protective coloration in large animals is illus- 
trated by the Somali giraffe (well shown by one of 
Lord Delamere’s photographs of a giraffesque thicket), 
by Grévy’s zebra, and by many deer; but the point is 
emphasised that in many other cases, such as the males 
of the Indian blackbuck, of the white-eared kob, and 
of the banting, no quite satisfactory reason can be 
assigned for the development of the characteristic 
colouring. This discussion naturally leads on to the 
essay which deals with stripes and spots in mammals, 
in regard to which it is shown that, while there may 
be a substratum of truth in the late Prof. Eimer’s 
“ longitudinal-spotted-transverse-uniform ’’ theory, it 
does not cover the facts. Thus transverse stripes 
appear in some of the most primitive of all mammals, 
and reappear in certain specialised groups where there 
is no evidence of a previous spotted stage having been 
passed through. From this theme we are led on to 
a discussion of ‘‘ How Arctic Animals Turn White,”’ in 
ccnnection with which the importance of Metchnilkoff’s 
researches on the rdle of phagocytes in the blanching 
ot hair is recognised. As to the protective value of 
the blanching there is no doubt. Under the striking 
title ‘* An Invisible Monkey,’’? Mr. Lydekker describes 
the remarkable black and white coloration of the 
guerezas (Colobus), which harmonises with the black- 
barked boughs thickly draped with pendent masses of 
grey lichen. ‘‘As the monkeys hang from the 
branches,’’ writes Dr. Gregory, ‘‘ they so closely 
resemble the lichen that I found it impossible to re- 
cognise them when but a short distance away.”’ 
Another essay is devoted to the peculiar hair of the 
sloths, where resemblance to a lichen-clad knot is en- 
hanced by a growth of green alge on the hairs. <A 
more difficult subject is the coloration of cowries, 
some lines in the manifold evolution of which the 
author tries to decipher. That banding was the 
original type seems to be indicated by the fact that 
it prevails in the young of the great majority of 
species. 
Other essays discuss monkeys’ noses and hand- 
prints, the aye-aye and the flying squirrels, the beaver, 
the quagga, cave-animals, giant land-tortoises, 
nursing habits of amphibians, scorpions and _ their 
antiquity. The only fault we wish to find with this 
delightful volume is that we can detect no arrange- 
ment in it, though, as our review shows, some group- 
ing is readily possible. 
Zoologists will find much valuable material in this 
volume, and many suggestions which are evidently not 
obiter dicta but the outcome of an expert’s reflection. 
But the author’s power of carrying the reader with 
him from the familiar to the unfamiliar should make 
his book welcome to a wider circle—to all interested 
in the problems of natural history. Our conviction is 
that there is much more education to be got out of 
a boolx like this, if read as carefully as it has been 
written, than out of many a treatise on mammals. It 
introduces the student to actual problems and to the 
method which an expert pursues in studying these. In 
conclusion, we would direct attention to the beautiful 
illustrations, e.g. of the aye-aye, of giraffes in covert, 
