254 
COLOUR IN NATURE 
CHAP. 
the reduced condition. The pigment, like carmine, 
behaves as an acid, being readily soluble in dilute 
alkalies, but insoluble in acids. 
Turacin is generally supposed to be confined to 
the plantain-eaters, but it has been also described 
by Krukenberg in one of the cuckoos (Dasylophus 
superciliosus ). The use, meaning, and origin are 
alike unknown ; its importance in coloration appears 
to be relatively slight, the feathers in which it occurs 
frequently showing bluish structural colour in addition 
to the red colour due to turacin. It is somewhat 
interesting to note that the family of the plantain- 
eaters is an exceedingly small one of very limited 
distribution—it occurs in Africa only. 
If turacin be boiled for a long time in air, it loses 
its red colour and becomes green, the change, accord¬ 
ing to Krukenberg, indicating the conversion into a 
new pigment. This new pigment he describes as 
being devoid of copper, but containing a considerable 
amount of iron ; its spectrum shows a single band, 
instead of the two of turacin itself. This green 
pigment was found by Krukenberg in the green 
feathers of Corythceola cristata , one of the Musopha- 
gidae in which turacin is absent, and of Corythaix 
albicristata , one in which it is present. This seems 
therefore to be one of those interesting cases of 
chemical relations existing between the different 
pigments of allied genera—a subject of which we 
know only too little. Church is, however, inclined 
to doubt the existence of an independent green 
pigment. 
Another interesting pigment of similarly restricted 
distribution is the red colouring-matter to which the 
