434 THE SPLEEN. [BOOK n. 



caused by stimulation of the medulla oblongata with a galvanic 

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

 been fully worked out, we have already sufficiently clear indi- 

 cations 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 the 

 organ, and the blood is at such times probably confined to the 

 well-established capillary passages, the metabolic changes which 

 it undergoes in the transit being comparatively slight. At 

 another time a larger quantity of blood enters the organ, and then 

 probably is let loose, so to speak, into the splenic pulp, there 

 to undergo more profound changes, and afterwards to be ejected by 

 the rhythmic contractions of the muscular trabeculse. 



Indeed, when the peculiar arrangements of the blood-vessels of 

 the spleen, with their large open venous networks, are borne in 

 mind, it seems in the highest degree probable that metabolic 

 events of great importance (possibly associated in some way with 

 the destruction or metamorphosis of the blood-corpuscles) take 

 place in the spleen, though at present we are unable to follow 

 them. And this view is supported by the somewhat peculiar 

 chemical characters of the spleen-pulp, which, in spite of its con- 

 taining a very large number of blood-corpuscles, differs markedly in 

 its chemical composition from either blood or serum. Thus a 

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

 way peculiarly associated with it seems to be present. The occur- 

 rence of this ferruginous proteid, accompanied as it is by several 

 peculiar but at present little understood pigments, rich in carbon, 

 bears out the histological conclusions (see p. 30) concerning the dis- 

 appearance of the red corpuscles. 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 blood - 

 corpuscles on the one hand, and from blood-serum on the other. 

 But perhaps the most striking feature of the spleen-pulp is its rich- 

 ness in the so-called extractives. Of these the most common and 

 plentiful are succinic, formic, acetic, butyric and lactic acids (these 

 may arise in part from the decomposition of haemoglobin), 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. No less suggestive is the fact that the increase of 

 uric acid in the urine during ague, and during ordinary pyrexia, 

 seems to run parallel to the turgescence, and therefore presumably 

 to the activity, of the spleen. But these facts are at present 

 suggestive only ; they point to an active metabolism, associated in 

 some way with digestion, taking place in the spleen ; exact informa- 



