186 ‘““AS PIGEONS FEED THEIR YOUNG.” 
with a substance secreted for that purpose by the parent 
animal; not, as in the mammalia, by the female alone, but 
also by the male, which perhaps furnishes this nutriment 
in a degree still more abundant. 
“Tt is a common property of birds, that both male and 
female are equally employed in hatching and in feeding 
their young in the second stage, but this particular mode 
of nourishment, by means of a substance secreted in their 
own bodies, is peculiar to certain kinds, and is carried on 
in the crop. 
“ Besides the dove kind, I have some reason to suppose 
parrots to be endowed with the same faculty, as they have 
the power of throwing up the contents of the crop, and 
feeding one another. 
“T have seen the cock parrakeet regularly feed the hen, 
by first filling his own crop, and then supplying her from 
his beak. Parrots, macaws, cockatoos, &c., when they are 
very fond of the person who feeds them, may likewise be 
observed to have the action of throwing up the food, and 
often do it. The cock pigeon, when he caresses the hen, 
performs the same kind of action as when he feeds his 
young, but I do not know if at this time he throws up 
anything from the crop. 
“During incubation, the coats of the crop in the pigeon 
are gradually enlarged and thickened, like what happens 
to the udder of females of the class mammalia, in the 
term of uterine gestation. On comparing the state of the 
