12 PIGEONS. 



equally employed in hatching and in feeding the young ; but this particular mode 

 of nourishment, by means of a substance secreted in their own bodies, is peculiar 

 to certain kinds, and is carried 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. I have seen the cock parroquet 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 class Mammalia in 

 the term of gestation. On comparing the state of the crop, when the bird is not 

 sitting, with its appearance during incubation, the difference is very remarkable. 

 In the first case, it is thin and membraneous ; but by the time the young are about 

 to be hatched, the whole, except what lies on the trachea, becomes thicker, and 

 takes on a glandular appearance, having its internal surface very irregular. It is 

 likewise evidently more vascular than in its former state, that it may convey a 

 quantity of blood sufficient for the secretion of the substance which is to nourish 

 the young for some days after they are hatched. 



"Whatever maybe the consistence of this substance when just secreted, it must 

 probably very soon coagulate into a granular white curd, for in such form have 

 always found it in the crop ; and if an old pigeon is killed just as the young ones 

 are hatching, the crop will be found as described, and in its cavity pieces of white 

 curd mixed with some of the common food of the pigeon, such as barley, beans, &c. 



"If we allow certain of the parents to feed the brood, tbe crop of the young 

 pigeons, when examined, will be discovered to contain the same kind of curdled 

 substance as that of the old ones, which passes from them into the stomach, 

 where it is digested. 



" The young pigeon is fed for a little time with this substance only, as about 

 the third day some of the common food is found mingled with it ; as the pigeon 

 grows older the proportion of common food is increased ; so that it is seven, eight, 

 or nine days old, before the secretion of the curd ceases in the old ones, and of 

 course no more will be found in the crop of the young ones. 



" I have called this substance curd, not being literally so, but resembling 

 that more than anything I know ; it may, however, have a greater resemblance to 

 curd than we are perhaps aware of, for neither this secretion, nor curd from which 

 whey has been pressed, seems to contain any sugar, and does not run into the 

 acetous fermentation. The property of coagulating is confined to the substance 

 itself, as it produced no such effect when mixed with milk. 



" This secretion in the pigeon, like all other animal substances, becomes putrid 



