100 



APPLIED PHYSIOLOGY 



is so ill-understood, and that diseases of the spleen are 

 the despair of the physician. 



The spleen is often regarded as a blood-forming organ. 

 In man, however, there is really no evidence that it can 

 form red cells. Eichly endowed as it is with adenoid 

 tissue in the form of the Malpighian bodies, there is no 

 doubt that it helps in the manufacture of lymphocytes, 

 but that is the only blood-forming function which can be 

 assigned to it. There is more reason for regarding 

 it as playing a part in the destruction of the blood, but 

 it is still open to question whether it does so actively or 

 whether it merely removes from the blood- stream the 

 de'bris or corpuscles which have been broken down 

 elsewhere. It is uncertain, in other words, whether the 

 spleen is an active agent in haemolysis or whether it is 

 only a blood-filter. Injection of poisons, such as chlorate 

 of potash, which disintegrate the blood corpuscles, causes 

 the spleen to enlarge, and the enlargement is in direct 

 proportion to the amount of blood destruction.* Similarly, 

 if bacteria or pigment particles be injected into the 

 vessels they are found to accumulate in the meshes of 

 the spleen. It would seem, therefore, as if the filter 

 function of the organ can be definitely established, and 

 it is believed that this explains its enlargement in such 

 diseases as malaria and enteric fever, in which blood 

 destruction is increased. On the other hand, there are 

 difficulties in the way of this view. The spleen is not 

 constantly enlarged in pernicious anaemia, and yet most 

 pathologists are agreed that in that disease blood destruc- 

 tion is greatly increased. The subject is still further 

 * Jawein, Virchow's Archiv, 1900, clxi. 461. 



