320 DR WALTER KIDD. 



pre-axial border, and the other more marked and passing to the 

 post-axia] border. The only divergence from this rule is that 

 on the third, fourth, and fifth first phalangeal segments the hair 

 slopes in the line of the digit (where it is under the shelter of 

 the digit lying in front of it in the majority of the actions of the 

 hand), instead of at right angles to the line of the digit. The 

 description of the slope on the nianus of man will suffice, with 

 change of terms, for that on the pes. It is easy to see that in 

 the ordinary position of the forearm and manus in walking, both 

 in the case of man and the higher apes, and in the course of 

 man's numerous manual avocations, the main tendency of these 

 will be to direct the slope as it is found. 



On the surface of the arm there is very little to notice as to 

 peculiarities. 



On the thigh also there is only one region — viz., the proximal 

 third of the extensor surface — where a peculiarity occurs. Man 

 shares this with many apes that have a habit of sitting. Here 

 the streams from the flexor surface curve round the axial and 

 pre-axial borders, much as we saw in the case of the forearm, 

 and they unite in the proximal third of the limb in a central 

 narrow stream, which passes directly to the tuberosity of the 

 ischium. This reversed stream in man, apes, and monkeys 

 would appear to be due to the mechanical effect on the slope of 

 hair of the attitude adopted in sitting, and in the case of long- 

 haired forms the action of gravity would assist it. 



On the leg there is little variation of slope from what is found 

 in animals such as monkeys. One large stream occupies the 

 whole of the length and circumference of this limb-segment, and 

 shows only one diverging line, which is not at all clearly marked, 

 at the fibular border of the limb on the extensor aspect. This 

 is situated where the mechanical effects of pressure in walking 

 among brushwood or any opposing ol)Stacles of that kind, with- 

 out covering on the limb, would produce some parting of the 

 streams. The absence of all peculiarities on this limb segment 

 either as to whorls, diverging lines, reversed slope, or others 

 such as are found elsewhere, is very suggestive, by its negative 

 evidence, of the effect found in those regions where clothing and 

 other forms of pressure are known to be in operation. Any 

 mechanical causes which would operate here would be such as 



