76 ANIMAL CURIOSITIES 
strains. In the case of the latter the trans¬ 
formed colour is of a permanent nature, and 
is brought about by the eradication of yellow 
or black pigments which together make green ; 
the absence of the yellow pigment, and the 
combining of the black with a white pigment 
secreted by certain cells, giving rise to the 
blue tint; and the yellow tint being produced 
by the loss of the black pigment. 
