Chap. YI. 
AFFINITIES AND GENEALOGY. 
193 
on the fore-arm is directed downwards or towards the 
wrist in the ordinary manner ; and in H. lar it is nearly 
erect, with only a very slight forward inclination ; so 
that in this latter species it is in a transitional state. 
It can hardly be doubted that with most mammals the 
thickness of the hair and its direction on the back is 
adapted to throw off the rain ; even the transverse hairs 
on the fore-legs of a dog may serve for this end when he 
is coiled up asleep. Mr. Wallace remarks that the con- 
vergence of the hair towards the elbow on the arms 
of the orang (whose habits he has so carefully studied) 
serves to throw off the raini^bwhen, as is the custom 
of this animal, the arms *are bent, with the hands 
clasped round a branch or over its own head. We 
should, however, bear in mind that the attitude of an 
animal may perhaps be in part determined by the 
direction of the hair ; and not the direction of the hair 
by the attitude. If the above explanation is correct in 
the case of the orang, the hair on our fore-arms offers a 
curious record of our former state ; for no one supposes 
that it is now of any use in throwing off the rain, nor in 
our present erect condition is it properly directed for this 
purpose. 
It would, however, be rash to trust too much to the 
principle of adaptation in regard to the direction of the 
hair in man or his early progenitors ; for it is impossible 
to study the figures given by Eschricht of the arrange- 
ment of the hair on the human foetus (this being the 
same as in the adult) and not agree with this excellent 
observer that other and more complex causes have 
intervened. The points of convergence seem to stand 
in some relation to those points in the embryo which 
are last closed in during development. There appears, 
also, to exist some relation between the arrangement 
VOL. i. o 
