J. W. H. Harrison 



241 



propionic acid) seems to be that utilised by enzymes to generate the 

 pigment so universal in its occurrence in the animal kingdom. This, 

 experimentally, not only by simple hydrolysis with acids, but also by the 

 action of ferments like tyrosinase, develops coloured compounds of the 

 humin type, and this is the kind of reaction we are to look for to account 

 for pigment occurrence in lepidopterous scales and hairs. That means 



1 



VWorKs 



Mormanb^ 



VEston 



Ormcfiby 



••.■•;~'/?t-0??'i 





Cuisborough 



VI 





Iron Hirxt. _ o 

 Moons -_ ••';;•- 



Woods . 'W' 



'KiWale 



$1 * Bo'+crsby 

 InqlebyN^. «N| 

 Creenhoti 



Fig. 13. General map of Middlesbrongh District. 



