1896.] Nerve-fibres ivJiich produce Contraction of the Spleen. 281* 



In one out of the four experiments contraction of the spleen was not 

 obtained by stimulation of the eleventh and twelfth postcervical pairs 

 •of nerve-roots, nor of the thirteenth root on the right side, although 

 obtained with all the other nerve-roots from the third to the four- 

 teenth postcervical inclusive. It is possible that this lack of effect 

 may have been due to some accidental cause which we were unable 

 to discover, or there may have been an individual peculiarity in the 

 nerve distribution in this animal. 



We have found that after intravenous injection of small doses of 

 nicotine, the effect upon the spleen of stimulating the nerve-roots 

 may entirely disappear, while stimulation of the splanchnics is still 

 •quite effective. We infer, therefore, that the nerve-fibres which pro- 

 duce contraction of the spleen have a cell station in the prevertebral 

 •chain of ganglia. 



We have not obtained any evidence regarding the nerve-root origin 

 •of the dilating or inhibitory fibres which we have shown to pass to 

 the spleen by the splanchnic nerves (see previous paper, p. 230). 



Conclusions. 



The muscular tissue of the spleen in the dog is innervated through 

 .an extraordinarily large number of nerve-roots, viz., from the third 

 postcervical to the fourteenth postcervical inclusive. 



The largest outflow, if we may judge by the amount of contraction • 

 produced, occurs from the fifth postcervical to the ninth postcervical 

 inclusive. 



Reasoning in the same way, the outflow is in each pair of nerve- 

 roots larger upon the left than upon the right side, i.e., it is not 

 bilaterally symmetrical. 



The outflowing fibres probably have a cell-connection in the main 

 ganglionic chain of the sympathetic. 



So far as we have been able to ascertain, there are no published 

 observations bearing directly upon the subject of this communication. 

 Dr. J. Rose Bradford attempted some years ago, in this laboratory, 

 to determine the spinal- root connections of the spleen with the aid of 

 Roy's oncometer, but he encountered considerable difficulty, and the 

 results which he was able to obtain were inconclusive. He informs 

 as, however, that he got contraction of the organ on stimulation of 

 nerve-roots in the thoracic region on both sides, although the limits 

 of the outflow were not decided, and that there was a tendency to 

 greater contraction on stimulation of the roots on the one side than 

 •on the other. 



