THE CELLULAR CHANGES OF AGE 61 



of bone, where the substance is made tougher and 

 stronger by the deposit of calcareous material. No- 





.*'* ' .; / *' 



S' ' ' ' 



FIG. 18. CROSS SKCTION OF THE ROOT OF A HAIR. AW, longitudinal, hbr, 

 circular fibres of the hair sheath ; bg, blood-vessels ; gl, hyaline sheath ; a-w, 

 outer layer of follicle ; iw, inner layer of follicle ; t, outer cuticle of the hair; 

 /, Huxley's layer of the follicle ; 2, Henle's layer of the follicle. X 300 diame- 

 ters. After Sobotta. 



thing like cartilage, nothing like bone, exists in the 



