THE VASCULAR GLANDS. 385 



the radicles of the veins, or end in lacunar spaces in the spleen-pulp, 

 from which veins arise. 



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 from the arterial capillaries is emptied into a system of inter- 

 mediate 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 tissue of the spleen is highly vascular, and 

 becomes readily engorged with blood: the amount of distention is, how- 

 ever, limited by the fibrous and muscular tissue of its capsule and 

 trabeculae, 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 -gL- to -g- 1 ^ inch in diameter. These are the Malpighian corpuscles 

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

 teries, of which, indeed, they may be said to be outgrowths (Fig. 263). 

 For while the sheaths of the larger arteries are constructed of ordinary 

 connective tissue, this has become modified where it forms an invest- 

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

 abundance of corpuscles, like lymph-corpuscles, contained in its meshes, 

 and the Malpighian corpuscles are but small outgrowths of this cyto- 

 genous or cell-bearing connective tissue. They are composed of cylin- 

 drical masses of corpuscles, intersected in 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 Malpighian cor- 

 puscle 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 fol- 

 lowing data: (1.) The large size which it gradually acquires towards the 

 termination of the digestive process, and the great increase observed 

 about this period in the amount of the finely-granular albuminous plasma 

 within its parenchyma, and the subsequent gradual decrease of this ma- 

 terial, seem to indicate that this organ is concerned in elaborating the al- 

 buminous materials of the food, and for a time storing them up, to be 

 gradually introduced into the blood, according to the demands of the 

 general system. 



(2. ) It seems probable that the spleen, like the lymphatic glands, is 

 engaged in the formation of blood-corpuscles. For it is quite certain 

 that the blood of the splenic vein contains an unusually large amount of 

 white corpuscles; and in the disease termed leucocythaemia, in which the 

 pale corpuscles of the blood are remarkably increased in number, there 

 25 



