310 Miss F. M. Durham. On the Presence of [Nov. 10, 



" On the Presence of Tyrosinases in the Skins of some Pigmented 

 Vertebrates. Preliminary Note." By FLOKENCE M. DURHAM. 

 Communicated by W. BATESON, F.E.S. Keceived November 

 10, Read December 1, 1904. 



(From the Balfour Laboratory, Cambridge.) 



In the course of an investigation of the " heredity of coat-colour in 

 mice," the necessity for further knowledge, concerning the formation 

 of pigment, became evident. 



In the hairs of these animals, there are apparently three pigments 

 (probably different forms of melanins), yellow., chocolate, and black. 

 The characteristic colour of each mouse is due to the presence of one 

 or more of these pigments. Thus, the yellow or "fawn" mouse has 

 only yellow pigment in its hairs, the chocolate mouse has only the 

 chocolate pigment, a black mouse has both chocolate and black pig- 

 ments, while the house mouse or " agouti " mouse has all three 

 pigments in its hairs (1). 



The differences in the nature of these pigments have not been 

 worked out as yet. Much work, however, has been done upon the 

 origin of melanins and on their relationships to the aromatic decom- 

 position products of proteids. 



In 1901, v. Fiirth and Schneider (2) showed that a tyrosinase could 

 be obtained from the blood of certain insects. This tyrosinase acted 

 upon a chromogen present in the blood, and converted it into a 

 melanin-like substance. When a solution of tyrosin in water was 

 treated with the ferment, a melanin-like body was also obtained. 

 According to the observations of Przibram (which are published with 

 those of v. Fiirth and Schneider), a tyrosinase can be extracted from 

 the ink-sac of. Sepia offidnalis. This ferment, acting in a like manner 

 upon a watery solution of tyrosin, yields a black pigment, probably a 

 melanin. Ducceschi (3) has shown that a similar ferment can be 

 obtained from the blood of Bombyx mori. 



Arguing from these facts, Cu^not (4), in a paper on the " Heredity 

 of Coat-Colour in Mice," suggests that the formation of pigment in 

 these animals is due to the presence, either of different chromogens 

 and one ferment, or of two different ferments and one chromogen. 

 The results of the action of the ferment on the chromogen would be 

 to produce the characteristic colour of the mouse. The alteration of 

 colour would be due either to the presence of a different chromogen, or 

 to the presence of a different ferment. 



It seemed worth while, therefore, to determine whether a ferment 

 could be extracted from animals, which, like the mouse, are deeply 

 pigmented in their coats ; and to test whether, if such a ferment could 



