XII 
THE COLOURS OF BIRDS 
251 
fish fat (cf. the statement as to the flamingo 
above). 
The Pigments of Birds, their Characters 
and Distribution 
As to the details connected with the pigments of 
birds, we may notice first that practically nothing is 
known of the melanin pigments. They are widely, 
perhaps universally, distributed in birds, give rise 
to all the dull and sober tints, colour all feathers 
displaying any beauty of marking, and are usually 
associated with feathers displaying structural colour. 
In birds as in mammals they form the groundwork 
of the coloration. Of their characters little is known. 
They may possibly be the same as the dark pig¬ 
ments of mammals ; an origin from haemoglobin has 
been suggested here as elsewhere in Vertebrates, but 
is not supported by very cogent evidence. 
The lipochromes are numerous and diverse, and 
have been chiefly investigated by Krukenberg. 
The most familiar is probably the red pigment, 
called by Bogdanow zoonerythrin, and by Wurm 
tetronerythrin, which colours the red feathers of the 
flamingo (Phcenicopterus antiquorum ), of the cardinal 
bird (Cardinalis virginianus ), and of many others, 
the red wattles in the male pheasant, etc. etc. The 
only other red pigment certainly of lipochrome 
nature which Krukenberg describes, is one which 
he calls “ araroth,” found in the red feathers of 
certain parrots, and differing only slightly from 
zoonerythrin. 
Of yellow lipochromes, on the other hand, he 
