GENERAL COMPARISON OF SYSTEMS. 



693 



in the course of an investigation into the innervation of the pelvic 

 viscera by Anderson and myself, results were obtained entirely in- 

 consistent with this theory. 1 Thus, for example, stimulation of the 

 sympathetic causes the most striking longitudinal contraction of the 

 vas deferens, and in the rabbit the most obvious inhibition of the longi- 

 tudinal coat of the descending colon ; and, on the other hand, stimulation 

 of the pelvic nerve causes in the rabbit, in certain circumstances, com- 

 plete and powerful contraction of the circular coat of the descending 

 colon and rectum. In one case only is there some primd facie ground 

 for the theory. The pelvic nerve causes great contraction of the recto- 

 coccygeal muscle ; and the sympathetic, if it has any effect at all, which 

 is not quite certain, has an inhibitory effect. 



We give in the following table a summary of the chief actions of the sym- 

 pathetic nerve on the one hand, and of the cranial and sacral autonomic nerves 

 on the other, in the regions of double supply. There are certain points which 

 are still doubtful, but the facts will serve to emphasise some conclusions 

 with regard to the autonomic nerves. 



A consideration of the facts given in the foregoing table shows that 

 there is no constant contrast between the function of the sympathetic 

 fibres on the one hand, and of the cranial and sacral on the other. In 

 the double supply the fibres from each source may have the same 

 action, or they may have a different action. If they have a different 

 action, either one or the other may be motor, and either one or the 

 other may be inhibitory. 



When, however, the fibres of one set arise from several nerves, we 

 never find any difference in function in the fibres from the several 

 nerves. Thus, all the sympathetic white rami which send fibres to a 



1 Jour a. Physiol., Cambridge and London, 1895, vol. xviii. p. 104 (on descending 

 colon) ; vol. xix. p. 74 (on bladder) ; vol, xix. p. 130 (on uterus and vas deferens). 



