ANATOMY OF TllK FOWL 47 



mother's iitorus. Jii tlie case of the bird there is no uterus in 

 the sense that we speak of it in higher animal life, henee no 

 uterine plaeenta, because there is no fetus developed in tlie 

 l)ird, but to take its place there is stored up an abundance 

 of food, taking the place of the deutoi)lasm and maternal nu- 

 trients of higher animal life. Nature has been elaborate in 

 storing up food for the embryo and the baby chick, for the 

 yolk is apparently almost wholly intended to be drawn upon 

 the first seventy-two hours of the baby chick's life or until it 

 is strong enough to follow the mother and till hatching of the 

 brood is over. An examination of a newly hatched bal)y 

 chick will show this yolk in the abdominal cavity and nuich 

 still unabsorbed. 



The active or functionating oviduct is a rather large, tortu- 

 ous tube varying in size and length, according to the size of 

 the hen, and filling a large part of the left half of the abdom- 

 inal cavity as illustrated in Fig. 13. In a single comb Rhode 

 Island Red pullet weighing six pounds and producing an egg 

 a day, the oviduct was found to measure twenty inches in 

 length. In a White Wyandotte pullet weighing five pounds, 

 and whose ovary and oviduct had not yet become active, the 

 oviduct measured but five inches. See Fig. 12, letter h. 



It can readily be seen that in a very fat hen with the intes- 

 tines, liver and other organs and a functionating ovary and 

 oviduct, as illustrated in Fig. 13, the abdominal cavity would 

 be crowded. When this crowded condition arises there may 

 be a partial or complete cessation of the function of the ovary 

 and oviduct, hence the hen ceases to lay. 



The oviduct originates at the anterior portion of the ab- 

 dominal cavity. Fig. 12, letter c, by an expansion at the ovary 

 in such a way as to receive the yolk when it is discharged from 

 the yolk sac of the ovary. This portion is anatomically known 

 as the funnel, ostium abdominale or infundibulum. The ovi- 

 duct may be divided into five portions, as follows: (1) The 

 principal albumen secreting portion, (2) a more constricted 

 portion, (3) the isthmus, (4) the shell gland portion, some- 

 times referred to as the uterus, and (5) the outer passage by 

 some known as the vagina. The vaginal or outer portion of 

 the oviduct is guarded ))y a rather well-developed sphincter 

 muscle. The oviduct is attached to the surrounding struc- 

 lui'es by dorsal and ventral ligaments. 



The oviduct consists of three main coats, namely: an ex- 

 ternal serous, a middle nniscular being made up of an outer 

 lougitudinal and an inner circular layer, and an internal 

 mucous coat which is thrown into folds both primary and sec- 



