THE URINE. 291 



like a sieve, the papillce of the pelvis of the organ ," or, more pro- 

 perly, the rounded ends of these cones project as so many papillae. 



" These papillae usually correspond in number with the lobes 

 which form the kidneys, and they convey the urine, secreted in the 

 colourless vessels of the cortex and " " the Bellinian tubes of the 

 medulla, into the infundibula" or little membranous canals which 

 at one end surround the duct or papilla, and at the other * unite 

 into a common pelvis. 



" The pelvis is continued into the ureters, which are mem- 

 branous canals, very sensible, lined with mucus, extremely dilat- 

 able, generally of unequal size in the human subject in different 

 parts h , and inserted into the posterior and inferior surface of 

 the bladder in such a way, that they do not immediately per- 

 forate its substance, but pass a short distance between the 

 muscular and cellular coats, which at that part are rather thicker 

 than elsewhere, and finally open into its cavity by an oblique 

 mouth. This peculiarity of structure prevents the urine from 

 regurgitating into the ureters from the bladder." 



As the ureters have a tendency to lose this obliquity of inser- 

 tion in proportion as the bladder is depleted, two long bands of 

 muscular fibres run from the back of the prostate gland to the 

 orifices of the ureters, and not only assist in emptying the bladder, 

 but, at the same time, pull down the orifices of the ureters, and 

 thus tend to preserve the obliquity. 1 When the bladder is dis- 

 tended, and the urine flows with difficulty into it, the fluid ac- 

 cumulates in the ureters, and, as the obliquity greatly lessens as 

 soon as the bladder is emptied, the urine then flows freely into 

 it, and persons, after making a large quantity of urine, thus very 

 soon make another quantity. 



" The urinary bladder*" oviform in the adult, but " varying 

 in shape according to age and sex, is generally capable, in the 

 adult, of containing two pints of urine. Its fundus, which in 

 the foetus terminates in the urachus, is covered posteriorly by 

 the peritonaeum. The other coats correspond with those of the 

 stomach. 



" The muscular consists of interrupted bands of fleshy fibres, 



8 " Eustachius, tab. xi. fig. 10." 



h " See Nuck, Adenographia, fig. 32. 34, 35. Leop. M. Ant. Caldani, Saggi 

 delV Accad. di Padova, t. ii. p. 2." 



1 Sir C. Bell, Med. Chir. Trans, vol. iii. 

 * " Duverney, CEuvres anatomiques, vol. ii. tab. i. iv " 



U 4 



