144 THE HisTcmr OF ANIMALS. [B. Tl 



the same period the cord which is attached to one choriou 

 falls off, and is separated from the animal, but the one which, 

 passes to the yolk remains suspended from the young bird 

 by a thin bowel, and a considerable portion of the yolk is 

 contained in the young bird, and some of it is found in the 

 stomach. 



7. At this period also they eject an excrementitious 

 matter into the external chorion, and contain it in the 

 stomach. The external excrement is white, the interaa. 

 yellow. At last the yolk, which has been continually 

 wasting and advancing, is entirely taken up and enclosed in 

 the young bird. So that portions of it may be observed in 

 the intestines of birds if they are dissected on the tenth 

 day after exclusion from the egg. But it is set at liberty 

 from the navel, nor does any communication remain, but 

 the whole is separated. About the before-mentioned period 

 the young bird sleeps, but it stirs itself, and looks up, and 

 chirps when it is touched, and the heart swells up with the 

 navel, as if the embryo were breathing. This is the manner 

 of the development of the chick in the egg. 



8. Birds also produce some barren eggs, as well as those 

 from sexual intercourse, but they produce nothing after in 

 cubation. This is particularly observed in pigeons. Double 

 eggs have two yolks ; in some a thin division of white pre 

 vents the yolks from mixing together ; others have not this 

 division, but touch each other. There are some hens which 

 always lay double eggs, and in these the peculiarities of the 

 yolks have been observed ; for a certain bird having laid 

 eighteen eggs, hatched two chickens from each of them, ex 

 cept those that were addled ; all the rest were productive, 

 except that one of the twin chickens was Irage and the 



other small in each. The last, however, was monstrous. 







CHAPTER IV. 



1. ALL the pigeon tribe, as the phatta and trygon, generally 

 produce two eggs ; the trygon and the phatta are those 

 which generally lay three. The pigeon lays, as I said, at 

 every season ; the trygon and the phatta in the spring, and 

 Hot more than twice. The second brood are hatched when 

 the first has been destroyed, for many birds destroy them. 



