172 Fatlo on Feathers — their Decoloration. 



very interesting and instructive series of specimens illustrating' 

 the economic uses of shells which he has caused to be exhibited 

 there. 



Explanation of Plate. 



Fig. I. — Japanese swine-herd blowing a Triton shell. 

 Copied by the late Dr. S. P. Woodward from a rare and 

 curious Japanese Book of Travels in Japan, preserved in the 

 library of the British Museum. 



Fig. 2. — Shell of Cassis rufa, with cameo (representing 

 Raphael and Fornarina) engraved upon its surface. Drawn 

 by the late Dr. S. P. Woodward from a specimen in the shell 

 gallery of the British Museum. 



The above have been carefully engraved by Mr. G. R. De 

 Wilde, whose skill as an artist is well known. 



FATIO ON FEATHERS— THEIR DECOLORATION. 



In our December number (p. 377) we give an account of 

 the important microscopical researches made by M. Fatio on 

 the te Forms and Colours of Plumage/' and we have now to 

 complete the subject by further extracts from M. Fatio' s 

 paper. 



M. Fatio commences a chapter on " Decoloration " by 

 explaining the extravasation of pigment spoken of in the earlier 

 part of his memoir. He says. " we have seen that in certain 

 cases of coloration by change of colour, the first pigment, in a 

 state of solution, was driven out by another and deeper pig- 

 ment, and forced to extravasate itself; and we have also seen in 

 other cases of coloration by augmentation of intensity, that the 

 dissolved pigment diffused itself in the spaces produced by the 

 absorption and evaporation of moisture, and that there was no 

 extravasation until the coloration was complete. We can there- 

 fore understand that each colour, as well as- each feather, has a 

 limited duration while the bird is alive, and one colour, without 

 being driven away by another, will nevertheless depart in. its 

 own turn. The feather which has performed its part succumbs 

 under the efforts which it has made ; its tissues deteriorate,, and 

 its pigment after being completely dissolved, disappears, driven 

 away by fresh accessions of greasy matter." 



" If a feather grown in the autumn does not fall in the 

 spring, and is not able to undergo a fresh coloration, it must 

 necessarily suffer a decoloration, more or less rapid and com- 

 plete." 



