36 



direction is perfectly straight downwards from head to end of 

 spine. This variation of slope is so peculiar and unexpected 

 (being found, as are nearly all the peculiarities of man's hair- 

 slope, in the foetus as well as the adult) that I have sought for 

 an explanation of this curious upward slope in the fact that 

 man, for one-third of his life approximately, i.e., during sleep, 

 lies on one side or the other, with his head more or less, 

 raised on pillows. This attitude, as we can see on reflection, 

 supplies the necessary downwards and inward traction on 

 the hair to slope them as described. The same explanation 

 meets another peculiar slope on the part of the back and 

 shoulder which is just behind the axilla where the slope of 

 hair is upward towards the neck and point of the shoulder. 

 The last area on the human body to which I will allude is 

 the side of the thorax and abdomen, when a very peculiar 

 parting line is found extending from the axilla in a slightly 

 curved direction until it reaches the level of the navel, and 

 there a whorl is to be found. From here it passes down 

 the side of the abdomen, where it is merged into another 

 marked parting line on the front of the thigh. On the 

 two sides of this parting line the hair slopes inwards 

 to the middle line of the abdomen and outwards to the 

 back as just described. This is peculiar to man, and is 

 found in only a very rudimentary way in apes, and I have 

 attributed it to the constant pressure and slight movement 

 one way or the other of the upper arm which in the 

 lateral position in sleep lies just over the parting line, and in 

 flexion the elbow lies over the point where the whorl just 

 mentioned is found. 



In concluding this short description of some of the 

 diversities of hair-slope found in a few regions of a few of the 

 leading hairy mammals, I must allude briefly to the aetiology 

 of these diversities. 



Looking at these facts from the scientific point of view, 

 we can only adopt one or other of the following two theories 

 of their causation— on the one hand they may be due to 

 selection, and on the other to the effects of use or habit, i.e., a 

 Darwinian or Lamarckian interpretation. Under the very 

 wide term selection maybe included — (1) natural or personal 

 selection ; (2"! sexual selection ; (3) germinal selection. I 

 would submit that such characters as these described are so 

 insignificant, in their importance to the chances of survival 

 of the individual mammals possessing them, as to be removed 



