Chap. VI. 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 rain, when, 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 



