THE PIE KIND. 237 



half maceration to- suit their tender appetites. 

 The heat of the bird's body, assisted by air, and 

 numerous glands separating a milky fluid, are 

 the most necessary instruments for this opera- 

 tion ; but, in proportion as the food macerates, 

 it begins to swell also, and the crop must of con- 

 sequence be considerably dilated. Still, however, 

 the air which is contained in it gives the bird a 

 power of contracting it at pleasure ; for if it were 

 filled with more solid substances, the bird could 

 have no power to compress it. But this is not 

 the case ; the bird can compress its crop at plea- 

 sure, and driving out the air, can thus drive out 

 the food also, which is forced up the gullet like 

 a pellet from a pop-gun. The young ones open- 

 mouthed receive this tribute of affection, and are 

 thus fed three times a-day. In feeding, the male 

 usually supplies the young female, while the old 

 female supplies the young of the opposite sex. 

 The food with which they are supplied is more 

 macerated in the beginning ; but as they grow 

 older, the parents give it less preparation, and at 

 last drive them out to shift for themselves. When 

 well fed, however, the old ones do not wait for 

 the total dismission of their young ; but in the 

 same nest are to be found young ones, almost fit 

 for flight, and eggs hatching at the same time. 



The fidelity of the turtle-dove is proverbial, 

 and makes the usual comparison of such poets as 

 are content to repeat what others have said be- 

 fore them j but the pigeon of the dove-house is 

 not so faithful; and, having been subjected to 

 man, it puts on licentiousness among its other 



