328 THE DUCTLESS GLANDS. 



the bloodvessels, nerves, and lymphatics enter, the fibrous coat 

 is prolonged into the spleen-substance in the form of investing 

 sheaths for the arteries and veins, which sheaths again are con- 

 nected with the trabeculcv before referred to. 



The spleen-pulp, which is of a dark red or reddish-brown 

 color, is composed chiefly of cells. Of these, some are granular 

 corpuscles resembling the lymph-corpuscles, both in general 

 appearance and in being able to perform amoeboid movements; 

 others are red blood-corpuscles of normal appearance or vari- 

 ously changed ; while there are also large cells containing 

 either pigment allied to the coloring matter of the blood, or 

 rounded corpuscles like red blood-cells. 



The splenic artery, which enters the spleen by its concave 

 surface or hilus, divides and subdivides, with but little anas- 

 tomosis between its branches, in the midst of the spleen-pulp, 

 at the same time that its branches are sheathed, as before said, 

 by the fibrous coat, which they, so to speak, carry into the 

 spleen with them. Ending in capillaries, they either com- 

 municate, as in other parts of the body, with the radicles of 

 the veins, or end in lacunar spaces in the spleen-pulp, from 

 which veins arise (Gray). 



On the face of a section of the spleen can be usually seen, 

 readily with the naked eye, minute, scattered, rounded or oval 

 whitish spots, mostly from ^ to g 1 ^ inch in diameter. These 

 are the Malpighian corpuscles of the spleen, and are situated on 

 the sheaths of the minute splenic arteries, of which, indeed, 

 they may be said to be outgrowths (Fig. 108). For while the 

 sheaths of the larger arteries are constructed of ordinary con- 

 nective tissue, this has become modified where it forms an in- 

 vestment for the smaller vessels, so as to be a fine retiform 

 tissue, with abundance of corpuscles, like lymph-corpuscles, 

 contained in its meshes ; and the Malpighian corpuscles are 

 but small outgrowths of this cytogenous or cell-bearing connec- 

 tive tissue. They are composed of masses of corpuscles, inter- 

 sected iu all parts by a delicate fibrillar tissue, which, though 

 it invests the Malpighian bodies, does not form a complete 

 capsule. Blood-capillaries traverse the Malpighian corpuscles 

 and form a plexus in their interior. The structure of a Mal- 

 pighian corpuscle of the spleen is, therefore, very similar to 

 that of lymphatic-gland substance (p. 284). 



The general resemblances in structure between certain of 

 the vascular glands and the true glands lead to the supposition 

 that both sets of organs pursue, up to a certain point, a similar 

 course in the discharge of their functions. It is assumed that 

 certain principles in an inferior state of organization are effused 



