THE FORMATION OF THE CONSTITUENTS OF BILE. 453 



a galvanic current or by means of asphyxia. Though the matter has not 

 yet been fully worked out, we have already sufficiently clear indications 

 that the flow of blood through the spleen is, through the agency of the 

 nervous system, varied to meet changing needs. At one time a small 

 quantity of blood is passing through or is being held by the organ, and the 

 metabolic changes which it undergoes in the transit are comparatively 

 slight. At another time a larger quantity of blood enters the organ, and is 

 let loose, so to speak, into the splenic pulp, there to undergo more profound 

 changes, and afterward to be ejected by the rhythmic contractions of the 

 muscular trabeculae. 



It is further obvious that these changes going on in the spleen must have 

 an important influence on the changes going on in the liver; it cannot be of 

 indifference to the latter organ, whether a relatively small quantity of blood, 

 relatively little changed, reaches it from the spleen, or whether it receives a 

 relatively large quantity of blood, profoundly altered by the changes which 

 it has undergone in the spleen-pulp. 



390. The chemical constituents of the spleen. Besides the chemical 

 bodies which one would expect to find in a vascular, muscular organ full of 

 blood, the spleen contains bodies, lodged apparently in the spleen-pulp, which 

 give it special chemical characters. One of the most important of these is 

 a special proteid of the nature of alkali-albumin, holding iron in some way 

 peculiarly associated with it. The occurrence of this ferruginous proteid, 

 accompanied as it is by several peculiar but at present little-understood pig- 

 ments, rich in carbon, which are partly present in the cells spoken of above 

 and partly deposited in the branched cells of the reticulum, appears to be 

 connected with the changes undergone by the haemoglobin which we shall 

 presently discuss. The inorganic salts of the spleen, or at least those of its 

 ash, are remarkable for the large amount of both soda and phosphates and 

 the small amount of potash and chlorides which they contain, thus differing 

 from those of blood corpuscles on the one hand, and from those of blood- 

 serum on the other. But perhaps the most striking feature of the spleen- 

 pulp is its richness in the so-called extractives. Of these the most common 

 and plentiful are succinic, formic, acetic, butyric, and lactic acids, inosit, 

 leucin, xanthin, hypoxanthin, and uric acid. Tyrosin apparently is not 

 present in the perfectly fresh spleen, though leucin is ; both are found when 

 decomposition has set in. The constant presence of uric acid is remarkable, 

 especially since it has been found even in the spleen of animals, such as the 

 herbivora, whose urine contains none. 



The richness of the spleen in these extractives is an indication of the 

 importance of the metabolic events with which the organ has to do ; but it 

 will be more profitable to discuss what goes on in the spleen in connection 

 with the metabolic changes in the other parts of the body, in the liver for 

 instance, than to attempt to lay down any so-called " functions " of the 

 spleen. When we confine our attention to the spleen itself we learn very 

 little ; thus the whole organ may be successfully removed without any very 

 obvious changes in the economy resulting. We may return, therefore, to 

 the discussion of the formation of the bilirubin of bile, and of the changes 

 undergone by haemoglobin, with which, as we shall see, the spleen is con- 

 nected, and which, moreover, has to do with the formation of other pig- 

 ments. 



THE FORMATION OF THE CONSTITUENTS OF BILE. 



391. Bile pigments. After extirpation of the liver no accumulation 

 of bile pigment or bile salts takes place in the blood. This is well shown in 



