CELLULAR ARRANGEMENT 151 



rolled between the finger and thumb, it will 

 pass along invariably in one direction, showing 

 that the cells are arranged to face one way. 

 If a hair be drawn along the lips one way and 

 then in the opposite direction, a difference will 

 readily be detected. 



In the hair of certain lower animals, when 

 this imbricated arrangement of the cells is more 

 pronounced, the hairs are better adapted to the 

 process of felting. 



On referring to the illustrations, Fig. 45 

 shows a vertical section of the human scalp. 

 Several hairs or portions of hair are seen in 

 situ. The original photograph is one of 26 

 diameters. The time of exposure was 2 minutes ; 

 the focal distance was 39 inches ; and the objec- 

 tive used was the Ij-inch without the eye-piece. 

 The next illustration (Fig. 46) is from a photo- 

 micrograph of 100 diameters. It shows the 

 transverse sections of several hairs, also sweat 

 glands and erector muscles besides several other 

 histological details; the focal distance was 50 

 inches, and the objective used was the J-inch. 



