PASSAGE OF URINE INTO THE BLADDER. 355 



tion is secreted, it propels that which is already in the tubes 

 onwards into the pelvis of the kidney. Thence through the 

 ureter the urine passes into the bladder, into which its rate 

 and mode of entrance has been watched in cases of ectopia 

 vesicse, i. e., of such fissures in the anterior and lower part of 

 the walls of the abdomen, and of the front wall of the bladder, 

 as exposed to view its hinder wall together with the orifices of 

 the ureters. Some good observations on such cases were made 

 by Mr. Erichsen. The urine does not enter the bladder at 

 any regular rate, nor is there a synchronism in its movement 

 through the two ureters. During fasting, two or three drops 

 enter the bladder every minute, each drop as it enters first 

 raising up the little papilla on which, in these cases, the ureter 

 opens, and then passing slowly through its orifice, which at 

 once again closes like a sphincter. In the recumbent posture, 

 the urine collects for a little time in the ureters, then flows 

 gently, and, if the body be raised, runs from them in a stream 

 till they are empty. Its flow is increased in deep inspiration, 

 or straining, and in active exercise, and in fifteen or twenty 

 minutes after a meal. 



The same observations, also, showed how fast some substances 

 pass from the stomach through the circulation, and through the 

 vessels of the kidneys. Ferrocyanide of potassium so passed 

 on one occasion in a minute : vegetable substances, such as 

 rhubarb, occupied from sixteen to thirty-five minutes ; neutral 

 alkaline salts with vegetable acids, which were generally de- 

 composed in transitu, made the urine alkaline in from twenty- 

 eight to forty-seven minutes. But the times of passage varied 

 much ; and the transit was always slow when the substances 

 were taken during digestion. 



The urine collecting in the urinary bladder is prevented 

 from regurgitation into the ureters by the mode in which these 

 pass through the walls of the bladder, namely, by their lying 

 for between half and three-quarters of an inch between the 

 muscular and mucous coats, and then turning rather abruptly 

 forwards, and opening through the latter, it collects till the 

 distension of the bladder is felt either by direct sensation, or, 

 in ordinary cases, by a transferred sensation at and near the 

 orifice of the urethra. Then, the effort of the will being di- 

 rected primarily to the muscles of the abdomen, and through 

 them (by reason of its tendency to act with them) to the urinary 

 bladder, the latter, though its muscular walls are really com- 

 posed of involuntary muscle, contracts, and expels the urine. 

 (See also p. 183.) 



