TBE URINARY APPARATUS. 



577 



several sources. The principal arteries come from the vesico-prostatic branch of 

 the internal pudic ; the umbilical artery also furnishes ramifications tliat reach 

 the fundus of the organ. The lymphatics pass to the sublumbar glands. The 

 nerves are furnished by the pelvic or hypogastric plexus, and the inferior branches 

 of the two last sacral pairs ; their twigs are spread more especially between the 

 muscular and mucous layers. 



Development. — The study of the development of the bladder is very interest- 



THE KIDNEYS AND BLADDER IN THE FCETUS OF SOLIPEDS. 



A, Supra-renal capsules; B, kidney; 6, ureter; <;, Madder; D, urachus. 1, abdominal aorta j 2, 

 external iliac artery; 3, umbilical artery; 4, umbilical vein. 



ing. It is narrower and more elongated in the foetus than the adult, and is 

 relatively more capacious during the whole period of intra-uterine life. It then 

 occupies the abdominal cavity as far as the umbilical opening, and is flanked by 

 the two umbilical arteries. Its posterior extremity alone enters the pelvis ; the 

 anterior extremity, forming a real neck, is continuous with the urachus, just as 



