Ill 





IV 



rfudi 



\ * \fr*v ^ ***s&s ^**'*^ 





*^- e i 



FIG. 185. FIVE STAGES IN THE DEVELOPMENT OF A HUMAN HAIR. 



a, papilla ; J, arrector pili ; c, the line is directed toward the primordial shaft ; rf, cells which 

 form the hair canal ; e, sebaceous gland ; /, hair germ ; <?, hair shaft ; A, Henle's layer ; *', Huxley's 

 layer ; , cuticle of the root sheath ; , inner root sheath ; m, outer root sheath in tangential sec- 

 tion ; 7?,, outer root sheath in longitudinal section ; 0, dermal root sheath, x 460. (After Stohr.) 

 212 



