THE SPLEEN. 161 



quently found, after death, an extensive alteration of these 

 structures. 



121. The spleen (figs. 57 and 78) is an organ engaged beyond 

 all question in the elaboration of the blood, and however 

 obscure the particulars of its function m'ay be, there is at 

 least more known about it than about the other organs 

 which have been briefly described. It is the largest of the 

 ductless glands, very variable in size, but usually from 5 to 

 7 oz. in weight. It increases largely some hours after eat- 

 ing, then gradually diminishes while fasting is continued. 

 It is a flattened oval body about 4 or 5 inches long, and 3 

 inches or more in breadth, and lies against the left end 

 of the stomach. It has a tough capsule, and consists of a 

 deep purple pulp imbedded in the meshes of a network of 

 fibrous trabeculse, which is highly elastic, and probably also 

 contains some muscular tissue. The pulp consists of granular 

 bodies of deep colour and about the size of blood corpuscles, 

 and nucleated corpuscles of very variable size, the larger of 

 which have several nuclei. In sections of spleens of the 

 domestic animals, and in spleens of young subjects, but not 

 so easily detected in the healthy adult human spleen, are 

 less deeply coloured spots like sago grains, called Malpighian 

 corpuscles of the spleen. They are collections of small 

 nucleated corpuscles in the sheaths of the arterioles. The 

 splenic artery and vein are very large for the size of the 

 organ. The venous blood is conveyed into the portal vein 

 to be sent through the liver. 



The very fact that the large supply of arterial blood sent 

 to the spleen is, after passing through that organ, transmitted 

 to the liver, seems to point to its having undergone, mean- 

 while, some great change which renders necessary the action 

 of the liver, as well as of respiration, before it is fit again to 

 traverse the tissues, and this idea is supported by examina- 

 tion of the blood. The blood in the splenic vein has the 

 serum of a reddish colour unlike that of any other blood, 

 and it contains less solid matter than other venous blood, a 

 circumstance easily explained on the supposition that there 

 is in the spleen a greater amount of chemical action, involv- 

 ing the formation of carbonic acid and water at the expense 

 of solid matter, than occurs in the tissues throughout the 

 H t, 



