THE SPLEEN AS AN ENDOCRIN ORGAN 671 



noted in many species of animals. As usual, contradictory literature has 

 been developed on this question (Meyer). In a large series of dogs we 

 have studied the effect of splenectomy on accessory spleens. In many cases 

 no changes in the accessory spleen were noted, while in others an enormous 

 increase in size occurred. This illustrates again the vicariousness of the 

 spleen. 



At present there seem to be but two positive statements that can be 

 made with regard to the function of the spleen. 



1. As the largest lymphoid organ in the body, it has the function of 

 lymphoid tissue in general. Whether or not the few definite and rather 

 constant changes occurring in the hematopoietic system after splenectomy 

 can be attributed wholly to the loss of this mass of lymphoid tissue cannot 

 be stated. Such, however, would s be the most probable explanation. 



2. The spleen has some function in relation to the portal system. 

 Whether or not this is purely mechanical, whereby arterial blood is 

 shunted through to the liver without becoming mixed with the products 

 of digestion, cannot be stated, but there is much evidence to make this 

 appear true. It is readily seen that for the two more or less definite 

 functions that can be ascribed to the spleen, it is not necessary to refer 

 to an intermediary in the form of an internal secretion. 



In conclusion it may be stated that while there is a possibility that the 

 spleen may elaborate a true internal secretion, there is at present not 

 enough evidence to warrant its classification as an endocrin organ. 



