546 PHYSIOLOGY . CHAP. 



corresponding to that of the lymphatic glands, thymus, and red 

 bone marrow which justifies us in assuming that the function of 

 all these organs (apart from their specific differences) is closely 

 allied, so that they are to some extent able to supplement each 

 other, or to act vicariously. Besides its peritoneal sheath the 

 spleen has a capsule, consisting of fibrous elastic and muscular 

 tissue. A number of trabeculae dip into the organ from the inner 

 surface of the capsule, dividing and subdividing, so that the 

 parenchyma is converted into an elastic and contractile network, 

 with large and small meshes, the hollow spaces of which contain 

 the so-called splenic pulp (Fig. 250). 



Fi<;. ^59. Vertical section through a fragment of human spleen, low magnification. (Kolliker.) 

 A, Peritoneal and librous capsule ; b, b, trabeculae ; c, c, Malpighian corpuscles, one of 

 which shows the transverse section, and the other the long section, of an artery ; d, injected 

 arterioles ; e, splenic pulp. 



When the spleen is cut across and squeezed, the pulp escapes, 

 looking like blackish coagulated blood, which after exposure to the 

 air assumes a lighter reddish hue. On examining a thin section 

 of spleen treated with dilute solution of potash under the micro- 

 scope, the splenic pulp is seen to be contained within the unequal 

 meshes of a lymphoid tissue that supports it, and is composed of 

 fringed connective cells, which ramify and anastomose among 

 themselves, and are in connection with the trabecular tissue 

 (Fig. 260). 



The splenic vein and artery are remarkable for their size 

 relative to the volume of the body which they irrigate. After 

 penetrating the hilum to the interior of the spleen by six or more 

 branches, they ramify dendritically, still within the trabeculae, 



