THE TIRO-GENITAL SYSTEM 175 



the posterior border of the kidney, and then maintains about the 

 same caliber throughout the rest of its course. 



Structure. The ureter wall is made up of three coats as follows: 

 mucous, muscular and fibrous. 



Function, The ureters serve as a passage way for the urine from 

 the kidneys to the cloaca. 



THE MALE GENERATIVE ORGANS (Fig. 54) 



The male generative organs in the fowl consist of two testicles 

 and an excretory apparatus, the vas deferens, for each. 



The Testicles. Location. The testicles are located in the sub- 

 lumbar region of the abdominal cavity, behind the lungs, below the 

 anterior extremity of the kidneys, and opposite the last three ribs. 



FIG. 54. The pelvic organs of a cockerel. A, Testes. B, Rectum. C, Cloaca. 

 D, Vas deferens. E, Kidney. F, Adrenal gland. G, Lungs. H, Ureter. 



Shape. The testicles are ellipsoid in shape; their size varies 

 with the different species of birds. The two in the same bird are 

 usually of the same size, though one testicle may be slightly larger 

 than the other. In a summary of a large number of weights of the 

 testicles of ten months old cockerels, the average weight was 0.021 

 pound each. The average measurements were 2 inches in the major 

 diameter and i inch in the minor diameter. In the cockerel before 

 sexual maturity, which is denoted by the male bird's crowing, the 

 testicles are very small. They resemble, in shape, a navy bean and 

 are yellowish-white in color. 



