Chemistry of Coat-Colour in Animals. 



43 



Ferrous sulphate added. 



Appearance after 12 hours. 



None 

 1 mgrm. 

 0-5 „ 



+ + 

 + 



+ + indicates strong reaction. 

 + indicates positive reaction. 

 — indicates no change. 



Although Miss Durham* obtained some catalytic reaction between her 

 skin extracts and ferrous salts, yet the above experiment shows that ferrous 

 salts inhibit the oxidation of tyrosine due to an oxidase ; a result which 

 is in agreement with Gortner'sf observations upon the action of tyrosinase 

 from meal-worms under similar conditions. 



Experiment III : The Action of other Chromogens. — The ferment fluid 

 (prepared as previously) was added to each tube. 





Appearance 



after 12 hours. 



Chromogeu added. 













Without H. : ; . 



"With H._0. : . 



None — — 



Tyrosine — + + 



p-cresol ++ + 



Adrenalin* — + 



Pyrocatechin (neutral) ... + + + + 



Tryptophane — ? 



Pvramidone — — 



Skatol — - 



ju-amidophenol | — — 



+ + indicates strong reaction. 

 + indicates positive reaction. 

 — indicates no change. 



* An aqueous extract of Burroughs and Wellcome's dry suprarenal glands was used. 



(d) Distribution and Nature of the Oxidase in Rabbits of Different Colours — 



An attempt was next made to discover whether the different coat- 

 colours in rabbits were due to a corresponding difference in the oxidases 

 which gave rise to them. For this purpose chocolate, blue and orange 

 rabbits were experimented with. Extracts from the chocolate skins were 

 rich in a ferment which appeared to be identical with that obtained from 

 black rabbits. After twelve hours this ferment gave a deep black ring 

 which gradually spread through the whole fluid, and 'at the end of some 



* Miss Durham, 'Proc. Eoy. Soc.,' vol. 74, p. 310 (1904). 

 t Gortner, 'Trans. Chem. Soc.,' vol. 97, p. 110 (1910). 



