vm THE EXCEETION OF UKINE 469 



from what we have been considering. Few physiologists since 

 Kohlrausch (1854) have taken it into serious consideration. 



Kohlrausch, in order to explain micturition without, or previous 

 to, desire, assumes that active intervention of the diaphragm and 

 abdominal muscles is necessary, in order by compression of the 

 intestines to lower and flatten the top of the bladder, and to pro- 

 duce the contraction of the detrusor. This muscle, by the fibres 

 inserted between the bundles of the sphincter, would act in a less 

 oblique direction, almost vertical to the fibres of the antagonist 

 muscle, and would thus succeed in overcoming the resistance and 

 opening the orifice of the urethra. Such an interpretation, how- 

 ever, appears to us to be totally erroneous, since it subordinates 

 the phenomenon to the active intervention of abdominal com- 

 pression. We have frequently convinced ourselves that it is easy 

 to micturate a few minutes after emptying the bladder, without 

 any modification of respiratory rhythm by which compression 

 could be exerted. Moreover, in this case the urine is evacuated 

 by a process which differs somewhat from that above. The 

 micturition caused by desire takes place directly the obstacles 

 (voluntary contraction of external sphincter, and reflex tonic 

 contraction of internal sphincter) which prevent the escape of the 

 urine are removed. Micturition without desire is, on the contrary, 

 preceded by an obscure sense of slow relaxation of the internal 

 sphincter, followed by a very long pause before the flow of urine 

 commences, during which a not unpleasant sensation of titillation 

 is felt near the orifice and the upper part of the urethra. That 

 Valentin is in almost complete agreement with this description of 

 micturition without desire is shown by the following passage : 

 " Si mingendi consilium coepimus, musculum clausorium vesicae 

 relaxatum esse primo sentimus, turn vero intervallum longius 

 breviusque intrat, quo lotium nondum defluit, denique lotium 

 ipsum ejicitur." Nothing is omitted here except the sense of 

 titillation previous to the passing of the urine. 



The only possible interpretation of the phenomena which 

 accompany micturition without desire appears to us to be as 

 follows : By the cerebral motor centres we voluntarily inhibit 

 the action of a spinal centre which exerts a tonic action upon the 

 internal sphincter of the bladder ; the relaxation or expansion of 

 this muscle permits a few drops of urine to trickle into the first 

 part of the urethra, which act on the sensory endings of the 

 urethral mucosa, and arouse the sense of titillation ; this sensation 

 then produces reflex contraction of the detrusor, which is followed 

 by evacuation. 



So that in this case also (if our interpretation be justified) 

 micturition is not entirely voluntary, but is a process which, 

 although initiated by the will, develops as a reflex act, independent 

 of the influence of the higher centres. 



