THE SKIN 



3o3 



other hand, it has been shown* that an extract can be made 

 from the skins of rats, rabbits, and guinea-pigs, which acts on 

 tyrosine in such a way as to give rise to pigment substances. 



"V'^' W; 



•.'. JS 









55 © 

 g £ 



From the conditions under which the conversion is most readily 

 effected, and the fact that the activity of the extract is at 

 once destroyed by boiling, the active agent is regarded as a 



* Loc. cit. 



