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remarkable to contrast from this point of view the zebra and 

 horse, so closely allied in form, the former presenting almost 

 no departure from a primitive type of slope, except a small 

 frontal whorl, and the horse such a large number as ten. It 

 is to be remembered that of all animals the domestic horse 

 is far the most locomotive in its habits, being nothing more 

 nor less than a living locomotive produced by man's work from 

 a wild stock by the use of applied biology for the same kind 

 of purpose, and by analogous methods as a locomotive 

 machine. The horse thus is nothing if not locomotive, not 

 only for its own needs, but mainly for those of man, who has 

 produced it. Here, if anywhere, can the effects of constant 

 muscular action in definite directions upon the direction of hair 

 be studied, and here it is found that the effects attributed to 

 that action, viz., whorls, featherings and crests, are found in 

 the highest degree. 



The Simiadce were shown to present a few peculiarities 

 of hair-slope, but far fewer than man, who is pre-eminent in 

 this matter. 



These preliminary observations of the facts of hair- 

 direction are necessary to the view that the hair of animals 

 is to be studied from the point of view of a stream. 



First. — The hair of animals grows at an appreciable 

 rate, not less than one inch in two months, the individual 

 hairs being pushed out from the hair-follicle in the direction 

 of least resistance. The stream, if it can be so called, is slow, 

 but so is the stream of a glacier, which in the higher Alps 

 flows at the rate of a foot a day in summer weather. 

 Another stream which flows at a variable rate is lava. 



Second. — The hair of an animal resembles the stream 

 of a river glacier or lava, in that it flows in the lines of least 

 resistance. There is a primitive and simple course which the 

 primitive hairy mammal must have possessed, something of 

 this may be learned from observation of the hairy covering of 

 an Ornithorhynchus. This primitive course of hair remains 

 partially in all animals, but in many it is broken up and 

 diverted by certain mechanical obstacles, as in a river the 

 stream may be altered by a half-sunken rock. This is 

 analogous to the constant underlying traction of very 

 divergent muscles, which produces whorls, featherings and 

 crests, in an animal's coat. Two chief obstacles, if one may 



