THE FUNCTIONS OF THE LIVER AND SPLEEN 451 



8. Heat Formation. The liver, by virtue of its manifold chemical 

 activities, produces heat. 



9. Venous Reservoir. Lastly, the liver acts as a venous reservoir 

 interposed in the portal circulation, and by virtue of this property 

 prevents overdistension of the right side of the heart. The blood 

 within it is expressed into the heart by the action of the diaphragm, 

 and the vigour of the hepatic circulation therefore depends very much 

 on the vigour of respiration that is on muscular exercise. In cases of 

 failure of the right side of the heart the liver becomes greatly engorged 

 with blood, and is felt pulsating below the margin of the ribs.. 



The Spleen. The exact nature of the main function of the spleen 

 is a matter of surmise. The gland can be extirpated from man and 

 animals without ill effects. It is stated to have been removed from 

 athletes in classical times, to prevent " stitch." It appears probable 

 that, after the operation, there is a compensatory overgrowth or 

 hypertrophy of lymphatic tissue. It has been shown recently that 

 after extirpation of the spleen more iron is lost than formerly in the 

 urine; the spleen may therefore be the regulator of the iron meta- 

 bolism of the body. There is some evidence that in the spleen the 

 effete red blood-corpuscles of the body are destroyed. It is question- 

 able whether in adult life the spleen plays any part in the formation 

 of red corpuscles, although it certainly does so in the foetus. By 

 virtue of its lymphatic tissue, the spleen gives origin to some of the 

 lymphocytes of the blood, and plays a considerable part in the purin 

 metabolism of the body. During the first hours following digestion 

 the spleen is swollen in size, acting like the liver as a blood-reservoir 

 in the portal circulation. The spleen rhythmically contracts. The 

 enlargement of the spleen in certain fevers e.g., malaria, typhoid 

 shows that it, like the lymph gland, is engaged in protecting the body 

 against bacterial invasion. 



