56 SCIENCE PROGRESS. 



is then usually a circular contraction, only occasionally a 

 longitudinal contraction. In the cat the same results are 

 obtained, but are less marked because the intestines are 

 more quiescent when exposed. The lower set causes 

 contraction of both circular and longitudinal coats of rectum 

 and descending colon and of the recto-coccygeal muscle. 

 In the cat the same results were obtained, though contrac- 

 tion of the circular coat was not so constant, and when 

 obtained was slight and took place slowly. With regard 

 to their course, Langley and Anderson have shown by the 

 degeneration method^ and by the nicotine method" that the 

 upper set of fibres run from the lumbar nerves to the inferior 

 mesenteric ganglia direct, and there nearly all end in cells 

 of that ganglion. Hence they run by branches from these 

 ganglia — as colonic nerves — directly to the viscus. In the 

 case of the second set of nerves, ganglion cells are present, 

 and are placed near the viscus itself. Thus the upper set 

 of nerve fibres are homologous with the related fibres con- 

 tained in the splanchnics, the lower set with those in the 

 vagi. With regard to the part played by the plexuses of 

 Meissner and Auerbach, they were not able to obtain any 

 special evidence of function. They conclude that the cells 

 of these plexuses do not belong to the sympathetic system, 

 but are of a different class. 



Vaso-viotor fibres for this part of the alimentary canal 

 are found in both the upper and lower set of fibres. 

 Stimulation of the upper set causes marked pallor of the 

 descending colon and rectum, and of the mucous mem- 

 brane of the anus. There are no vaso-dilators in this set. 

 The cells on the course of the fibres are in the inferior 

 mesenteric ganglion, or in the colonic nerves near their 

 origin from that ganglion. The sacral set of fibres contain 

 vaso-dilator fibres for the rectum, but they were not observed 

 for the colon. The effect was not very marked in the cat, 

 but rather better in the rabbit. These fibres have cells on 

 their course placed near their termination in the viscus. 



Steinach, for the frog finds nerves to the rectum in both 



^ Journ. of Phys., vol. xvii., p. 177, 1894. 

 ^ Il>id., vol. xix., p. 131, 1895. 



