THE VASCULAR GLANDS. 6 



system. Of the cells some are granular corpuscles resembling the lymph 

 corpuscles, more or less connected with the cells of the meshwork, both 

 in general appearance and in being able to perform amoeboid movements; 

 others are red blood-corpuscles of normal appearance or variously changed ; 

 while there are also large cells containing either a pigment allied to the 

 coloring matter of the blood, or rounded corpuscles like red blood- cells. 



The splenic artery, after entering the spleen by its concave surface, 

 divides and subdivides, with but little anastomosis between its branches; 

 at the same time its branches are sheathed by the prolongations of fibrous 

 coat, which they, so to speak, carry into the spleen with them. The 

 arteries send off branches into the spleen-pulp which end in capillaries, 

 and these either communicate, 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). 



The walls of the smaller veins are more or less incomplete, and readily 

 allow lymphoid corpuscles to be swept into the blood-current. "The 

 blood traverses the network of the pulp, and interstices of the lymphoid 

 cells contained in the latter, in the same manner as the water of a river 

 finds its way among the pebbles of its bed: the blood from the arterial 

 capillaries is emptied into a system of intermediate passages, which are 

 directly bounded by the cells and fibres of the network of the pulp, and 

 from which the smallest venous radicles with their cribriform walls take 

 origin" (Frey). The veins are large and very distensible: the whole tis- 

 sue of the spleen is highly vascular, and becomes readily engorged with 

 blood: the amount of distension is, however, limited by the fibrous and 

 muscular tissue of its capsule and trabeculse, which forms an investment 

 and support for the pulpy mass within. 



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 -gV to V inch in diameter. These are the MalpigMan corpuscles 

 of the spleen, and are situated on the sheaths of the minute splenic arte- 

 ries, of which, indeed, they may be said to be outgrowths (Fig. 254). For 

 while the sheaths of the larger arteries are constructed of ordinary con- 

 nective tissue, this has become modified where it forms an investment 

 for the smaller vessels, so as to be composed of adenoid tissue, with abun- 

 dance of corpuscles, like lymph-corpuscles, contained in its meshes, and 

 the Malpighian corpuscles are but small outgrowths of this cytogenous or 

 cell-bearing connective tissue. They are composed of cylindrical masses of 

 corpuscles, intersected in all parts by a delicate fibrillar tissue, which 

 though it invests the Malpighian bodies, does not form a complete cap- 

 sule. Blood-capillaries traverse the Malpighian corpuscles and form a 

 plexus in their interior. The structure of a Malpighian corpuscle of the 

 spleen is, therefore, very similar to that of lymphatic-gland substance. 



Functions. With respect to the office of the spleen, we have the 



