58 SCIENCE PROGRESS. 



in these nerve roots. In the cat stimulation of these fibres 

 may result in contraction or dilatation of the sphincter. 

 The nerve cells on the course of the fibres of the upper set 

 lie either in the superior mesenteric ganglia or in the ganglia 

 in the hypogastric nerves. The cells on the lower set lie 

 near the peripheral termination of the fibres. 



Spleen. — Until the present year our knowledge of the 

 innervation of this organ rested chiefly upon the work of 

 Bulgak and Roy. Bulgak ^ relied upon direct observation 

 of the spleen and showed that the nerves in the gastro- 

 splenic omentum were of two kinds, afferent and efferent. 

 Stimulation of the peripheral end of the latter caused a 

 marked contraction of the spleen which was observed to 

 pale in colour, its edges became more rounded and irregu- 

 larities on its surface appeared. Stimulation of the peri- 

 pheral end of the former nerves caused no effect, but when 

 the central end was stimulated a marked reflex contraction 

 was produced. He obtained big contractions by stimu- 

 lating the semilunar ganglion or the peripheral end of the 

 greater splanchnic on the left side. He observed no con- 

 traction on stimulating the peripheral end of the lesser 

 splanchnic on the left side, or of either splanchnic on the 

 right side. He traced these fibres still further backwards 

 in their course, and localised them to the third to tenth 

 thoracic anterior roots of the left side only, stating that no 

 contraction was to be obtained by stimulating any of the 

 roots above or below these or on the opposite side. He 

 next examined the effect of the vagus upon the spleen and 

 in opposition to previous observers found that stimulation 

 of the nerve did not produce any contraction. The nerve 

 was stimulated both above and below the point where it 

 gave off its cardiac branches. Stimulation of the central 

 end produces a large contraction, an effect which he sug- 

 gests, is due to the interference with respiration, for he had 

 previously observed that the splenic contractions were 

 greatly increased by a venous condition of the blood. 

 Roy ^ studied the rhythm and innervation of this organ by 



1 Virchow Archiv, lxi.x., p. i8i, 1877. 



'^ Joiirn. of Physiol., vol. iii., p. 203, 1881. 



