"AS PIGEONS FEED THEIR YOUNG." 1 87 



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 membranous, but by the time 

 the young are about to be hatched, the whole, except 

 what lies on the trachea or windpipe, becomes thickened, 

 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 this sub- 

 stance, which is to nourish the young brood for some days 

 after they are hatched. Whatever may be the consistence 

 of this substance when just secreted, it most probably 

 soon coagulates into a granulated white curd, for in such a 

 form I 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 above 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 either of the parents to feed the young, its 

 crop, when examined, will be discovered to contain the 

 same curdled substance, which passes thence into the 

 stomach, where it is to be digested. The young pigeon is 

 fed for some time with this substance only, and about the 

 third day some of the common food is found mingled with 

 it ; and as the pigeon grows older, the proportion of 

 common food is increased, so that by the time it is seven, 

 eight, or nine days old, the secretion of the curd ceases in 



