MOTOR FUNCTIONS OF THE BULBO-SACRAL O UTFLO IV 59 



nerve brought about a contraction of the bladder reflexly through 

 the isolated inferior mesenteric ganglion. Langley and Anderson 

 investigated this apparent reflex and not only confirmed the fact, 

 but showed also that the reflex was not confined to the bladder, 

 for there occurred distinct pallor of the rectum and contraction 

 of the internal sphincter muscle of the anus, when the cut hypo- 

 gastric was stimulated. The part of the bladder involved was 

 the trigonal area, and the reflex in all cases disappeared when 

 nicotine was injected, showing that nerve cells were involved in 

 the course of the reflex. 



Further they showed that the effect of stimulation of the 

 lumbar splanchnics was not confined to one side, proving that a 

 stimulation of connector fibres could reach the opposite hypo- 

 gastric nerve by way of the paired inferior mesenteric ganglia. 

 Finally, by the method of degeneration, they showed that the 

 hypogastric fibres, on which the reflex depended, had their nutri- 

 tive cells in the central nervous system and that, therefore, when 

 the lumbar splanchnics were cut on the one side and time allowed 

 for their degeneration, the Sokownin reflex was no longer possible. 

 The conclusion to which they came was that this reflex is not a 

 true reflex in the ordinary sense of the word, but one brought 

 about through the connector fibres of the lumbar splanchnics 

 only ; the explanation being that a connector fibre in the lumbar 

 splanchnic nerve passes along the hypogastrics to connect with a 

 motor nerve cell of the internal sphincter ani muscle, which is 

 situated near the muscle itself. This fibre gives off a collateral 

 to connect with a nerve cell in the inferior mesenteric ganglion 

 of the opposite side, which supplies motor fibres to the internal 

 sphincter ani of that side. This collateral is excited because it 

 is part and parcel of the same axis cylinder as that of the fibre 

 stimulated. A similar argument applies in the case of the reflex 

 on the trigonal part of the bladder and the muscles of the rectal 

 blood vessels. They have never seen any such reflex on the 

 uterus, or any of the internal genital organs, which would imply 

 that no nerve cells supplying motor fibres to these muscles are 

 situated in the inferior mesenteric ganglia, or if so, that there 

 is no connexion between the two sides of the body. 



In addition to this reflex Langley has found exactly similar 

 phenomena in ganglia of the lateral chain. 



These axon reflexes constitute one of the chief arguments in 



