50 



multitude of vessels iii thc roots, and thenerves traceable to the bulbs 

 of hair ; the direct action of the will upon hau" and feathers in cer- 

 tain animals; the fact of hair becoming an organ of sensation in 

 plica Polonica ; the efFect of impressions of the mind and ofdisease 

 upon the hair in man ; the internal preparatory process for re- 

 flecting particular colours ; and the changes produced by sexual 

 periods. He further inquired whether, as hair grows frora thec«/2* 

 and passes through the rete mucosum, this latter membrane may not 

 be the depository of the colouring matter, vvhence it is taken up 

 perennially by hair and by most feathers, but onlyat certain seasons 

 by others. VVhether, however, the change of colour in feather and 

 hair be ovving to the diffusion of a ne\v body through them, or to a 

 modification in the arrangement of their primary molecules causing 

 them to reflect other rays, — in either case, he apprehends^ organic 

 action is equally implied. 



