VIII 



THE EXCRETION OF URINE 



407 



established communication between the bladder and a Gad's metal 

 manometer which recorded the intravesical pressure on a revolving 

 drum. The subject was then invited to micturate, and the urine 

 which flowed from the urethra down the side of the catheter 

 was run into a filter communicating with a bottle connected 

 at atmospheric pressure with a Gad's plethysmograph, which re- 

 corded the flow of urine on the same drum. The arrangement is 

 shown in Fig. 128. By this ingenious method Rehfisch was able 





ST 



Fio. 128. Apparatus usediby Rehfisch to study micturition in man. The catheter K, introduced 

 into the bladder B, communicates either with the syringe N or the manometer .If, according as 

 the two-way tap D is set in position /. or II. The funnel T receives the urine which flows 

 from the urethra down the side of the catheter, and leads it through tube (.' to flask F, whence 

 the pressure is transmitted by tube L to the plethysmograph V. The manometer records the 

 curve of vesical pressure A, Ii, on the revolving cylinder, and the plethysmograph the volume 

 curve of the urine C, D. 



to compare the pressure curve with that of vesical evacuation, 

 during voluntary micturition. 



If the opening of the sphincter, as expressed in the rise of the 

 lever, always coincided with the moment at which pressure in the 

 bladder became maximal, this would show it to be the passive 

 effect of the increased tension in the bladder, and would be an 

 experimental demonstration of the theory by which micturition 



