PHYSIOLOGY OF THE LIVER AND SPLEEN. 827 



has some connection with the hfe-history of the red corpuscles and 

 of the hemoglobin contained in them.* Splenectomy is followed 

 always by an anemic condition that lasts, however, for a short 

 period only. After some months the number of red corpuscles re- 

 turns to normal. On the other hand, injection of splenic extracts 

 causes a distinct although short-lasting increase in the blood- 

 count. It is stated also that after splenectomy abnormal amounts 

 of iron are excreted and that there is a diminution in the quantity 

 of bile-pigments. Asher f believes that the spleen furnishes a sub- 

 stance wliich activates the processes in the liver concerned with 

 the hemolysis of the red corpuscles and the transformation of the 

 hemoglobin. The most definite facts known about the spleen are in 

 connection with its movements. It has been shown that there is a 

 slow expansion and contraction of the organ synchronous with the 

 digestion periods. After a meal the spleen begins to increase in size, 

 reaching a maximum at about the fifth hour, and then slowly returns 

 to its previous size. This movement, the meaning of which is not 

 known, is probably due to a slow vasodilation, together, perhaps, 

 with a relaxation of the tonic contraction of the musculature of the 

 trabeculse. In addition to this slow movement, Roy J has shown 

 that there is a rhythmical contraction and relaxation of the organ, 

 occurring in cats and dogs at intervals of about one minute. Roy 

 supposes that these contractions are effected through the intrinsic 

 musculature of the organ, — that is, the plain muscle tissue present 

 in the capsule and trabeculse, — and he believes that the contractions 

 serve to keep up a circulation through the spleen and to make its 

 vascular supply more or less independent of variations in general 

 arterial pressure. The fact that there is a special local arrangement 

 for maintaining its circulation makes the spleen unique among the 

 organs of the bod}'^, but no light is thrown upon the nature of the 

 function fulfilled. The spleen is supplied richly with motor nerve 

 fibers which when stimulated either directly or reflexly cause the 

 organ to diminish in volume. According to Schaefer,§ these fibers 

 are contained in the splanchnic nerves, which carry also inhibitory 

 fibers whose stimulation produces a dilatation of the spleen. 



The chemical composition of the spleen is complicated, but sug- 

 gestive. Its mineral constituents are characterized by a large 

 percentage of iron, which seems to be present as an organic compound 

 of some kind. Analysis shows also the presence of a number of fatty 

 acids, fats, cholesterin, and, what is perhaps more noteworthy, a 

 number of nitrogenous extractives belonging to the group of purin 



* Consult Musser and Krumbhaar, "Journal of Exp. Medicine," 18, 487, 

 1913, and 20, 108, 1914; also Pearce and Pepper, ibid., 20, 19, 1914. 

 t Ebnother, "Biochemische Zeitschrift," 72, 416, 1916. 

 j "Journal of Physiology," 3, 203, 1881. 

 § Ibid., 20, 1, 1896. 



