366 MANUAL OF PHYSIOLOGY. 



depends on the number of the white cells which are packed in 

 the meshes of this perivascular adenoid tissue. 



The splenic pulp consists of a system of communicating lacunar 

 spaces lined with endothelium. Into these spaces the blood is 

 poured from the arteries, and thus mingles with vast numbers of 

 white cells. Besides the ordinary blood disks and the white cor- 

 puscles or lymph cells, many peculiar cells are found in the spleen 

 pulp. Some of these look like lymph cells containing little masses 

 of haemoglobin, and appear to be transitions from the colorless 

 to the red corpuscles, whilst others, small, misshapen, red cor- 

 puscles, are regarded as steps in a retrograde change in the disks. 

 But few, if any, lymph channels lead from the spleen pulp, and 

 only a relatively small number pass out from the hilus, so that 

 the splenic artery and vein must be regarded as taking the place 

 of the afferent and efferent lymph channels. 



Chemical examination shows the splenic pulp to have remark- 

 able peculiarities. Although so full of blood, which is generally 

 alkaline, the spleen is acid in reaction, and contains a great quan- 

 tity of the oxidation products (so-called extractives) commonly 

 found as the result of active tissue change. The chief of these 

 are uric acid, leucin, xanthin, hypoxanthin, inosit, lactic, formic, 

 succinic, acetic, and butyric acids. It also contains numerous 

 pigments, rich in carbon, but little known, which are probably 

 the outcome of destroyed haemoglobin. A peculiarly suggestive 

 constituent is an albuminous body containing iron. The ash is 

 found to contain a considerable quantity of oxide of iron, to be 

 rich in phosphates and soda, with but small quantities of chlorides 

 and potassium. 



If the blood flowing in the artery to the spleen be compared 

 with that in the vein, the difference gives us the changes the 

 blood has undergone in the organ, and hence is of great import- 

 ance. In the blood of the vein is found an enormous increase in 

 the number of the white corpuscles (1 white to 70 red in the vein, 

 as against 1 to 2000 in the splenic artery). The red corpuscles 

 from the vein are smaller, brighter, less flattened than those of 

 ordinary blood ; they do not form rouleaux, and are more capable 

 of resisting the injurious influence of water. The blood of the 



