THE STORY OF DIGESTION 55 



to the lymphatic glands which have already been 

 described. It is one of the ductless glands of the 

 body, that is to say, it possesses no tube or duct 

 issuing from it like the liver or sweetbread, and 

 therefore does not elaborate any secretion to be 

 poured into the digestive tube or other system of 

 the body. But the spleen is well supplied with 

 bloodvessels. A very large artery enters it and a 

 very large vein leaves it, so that a continuous 

 current of blood is always passing through this 

 organ. It is found that the blood leaving the spleen 

 has a larger number of white cells or corpuscles 

 than the blood which enters it, so that we may 

 regard the spleen as a manufactory of the white 

 corpuscles in question. Furthermore, it would seem 

 that in the spleen the old worn-out red corpuscles 

 of the blood are disposed of, because examination of 

 the spleen substance seems to show these corpuscles 

 in all stages of breakdown. Some authorities are 

 of opinion that the spleen also aids in the manufac- 

 ture of red corpuscles, although these latter are 

 known to be elaborated in other organs of the body. 

 The spleen, it may be added, is capable of being 

 removed from the body of animals without their 

 existence being materially impaired. The explana- 

 tion is to be found in the idea that, as the spleen is 

 really a lymphatic gland, its absence is compensated 

 for by the work of the other glands of the system to 

 which it belongs. 



