382 USES OF THE LIVER DUCTLESS GLANDS 



pulp, but nothing definite is known of their mode of termination. 

 When these nerves are stimulated, the non-striated muscles in the sub- 

 stance of the spleen are thrown into contraction. 



Some Points in tJie Chemical Constitution of the Spleen. Little has 

 been learned in regard to the probable uses of the spleen from analyses 

 of its substance ; and it would therefore be out of place to discuss its 

 chemical constitution very fully. Cholesterin has been found constantly 

 and in considerable quantity, and the same may be said of uric acid. 

 In addition, chemists have extracted from the substance of the spleen 

 various proteids, hypoxanthin, leucin, tyrosin, lecithin, jecorin, a peculiar 

 crystallizable substance called, by Scherer, lienin, crystals of hematoi- 

 din, lactic acid, acetic acid, butyric acid, inosite, amyloid matter and 

 some indefinite fatty matters. 



Variations in the Volume of tfie Spleen. One of the theories in 

 regard to the uses of the spleen, which merits some consideration, is 

 that it serves as a diverticulum for the blood when there is a tendency 

 to congestion of the other abdominal viscera. 



It has been shown that the spleen becomes enlarged in dogs four or 

 five hours after feeding, that its enlargement is at its maximum at about 

 the fifth hour and that it gradually diminishes to its original size during 

 the succeeding twelve hours ; but it is not apparent how far these 

 changes are important or essential to normal digestion and absorption. 

 Experiments have shown that animals may live, digest, and absorb 

 alimentary matters after the spleen has been removed, and this has 

 been observed even in the human subject. In view of these facts, it 

 can not be assumed that the office of the spleen as a diverticulum for the 

 blood is essential to the proper action of the other abdominal organs. 



Changes in the volume of the spleen may be produced by operating 

 on the nervous system, chiefly through the vasomotor nerves. Section 

 of the nerves at the hilum increases the size of the spleen by increasing 

 the quantity of blood ; and stimulation of these nerves produces con- 

 traction of the spleen. It is said that stimulation of the bulb dimin- 

 ishes the size of the spleen, and that the same result can be produced 

 by reflex action, stimulating the central ends of the pneumogastrics or 

 of various sensory nerves, provided the splanchnic nerves be intact. 

 Starting from the bulb, the nerve-fibres that influence the size of the 

 spleen pass down the spinal cord to the lower dorsal region, enter the 

 semilunar ganglion by the left splanchnic and are distributed to 

 the spleen through the splenic plexus. 



Rhythmical contraction of the spleen, occurring about once a 

 minute, has been observed in dogs and cats (Roy) and was supposed 

 to assist the circulation in this organ ; but there is no evidence that 



