fc 



THE LYMPHATIC AND MUCOUS SECRETIONS 905 



It has also been established that in embryonal life the spleen pos- 

 sesses the function of a hematopoietic organ and that its power of form- 

 ing corpuscles may be called into play during adult life whenever 

 required. In fact, it seems to retain this function during the entire life 

 of some animals, because it embraces cells which display all the charac- 

 teristics of the hem^toblasts of the bone marrow. In these animals, the 

 removal of the spleen gives rise to a hypertrophy of the bone marrow. 



The spleen is one of the organs in which the red corpuscles of the 

 blood undergo disintegration. This inference is based upon the fact 

 that the pulp contains an abundance of these cells in varying stages of 

 degeneration. This statement, however, is not meant to imply that 

 this organ is the chief place in which the red corpuscles are destroyed, 

 nor that their disintegration actually leads to a liberation of their color- 

 ing material, the hemoglobin. More plausible is the view which holds 

 that the spleen merely accomplishes the fragmentation of the worn 

 out corpuscles which are then more fully reduced in the liver. Un- 

 der pathological conditions, however, its destructive power may be 

 greatly increased, as is proved by the fact that it then becomes a 

 depository for iron which can only be derived from the red corpuscles. 

 Such a condition is developed in the course of the disease, known as 

 pernicious anemia. It has also been demonstrated that the spleen 

 aids in the formation of uric acid, because the removal of the kidneys 

 gives rise to an accumulation of this substance within this organ. 



Attention has previously been called to the spongy character of the 

 pulp of the spleen which enables this organ to accommodate enormous 

 quantities of blood. With the help of the smooth musculature of its 

 capsule and trabecule, this blood is again returned into the general 

 circulation. For this reason, it may be conjectured that this organ 

 acts as a vascular reservoir or diverticulum for the digestive organs or 

 the portal circulation. Its smooth musculature is innervated by 

 fibers which closely invest the splenic arteries and are derived from the 

 celiac ganghon of the solar plexus. In this way, the spleen is brought 

 into correlation not only with the other portal organs but also with 

 the central nervous system. Stimulation of these nerves evokes a 

 vaso-constrictor reaction which prevents the arterial blood from 

 entering the spleen, while its venous tubules are emptied. The 

 division of these nerves, on the other hand, gives rise to an engorge- 

 ment of this organ and a withdrawal of a considerable quantity of blood 

 from the general circulation. Of special interest is the fact that these 

 alterations in its vascularity may also result in consequence of reflex 

 stimulation; in fact, Roy^ and others state that they appear with 

 almost rhythmic regularity at the rate of one in about every minute. 

 Since the mechanical effect of these ordinary wave-like contractions 

 upon the general circulation cannot be considerable, they must be more 



1 Jour, of Physiol., iii, 1881, 203, also Schaefer and Moore, Jour, of Physiol., 

 XX, 1896. 



