'em. 



286 ABSORPTION AND SANGUIFICATION. 



the valves, with which they are copiously furnished. Moreover, it is 

 probable that the general movements of the body may concur with the 

 contractile power of the absorbent vessels themselves, to urge their con- 

 tents onwards; for .almost every change in position must occasion 

 increased pressure on some portion of them, which will propel the fluid 

 contents in the sole direction permitted by the valves, and thus give 

 them an additional impulse towards the trunks, in which they are col- 

 lected for delivery into the blood-vessels. 



3. Of the Spleen j and other Glandular Appendages to the Lymphatic Syst 



505. The structure and functions of the Spleen, and of certain other 

 organs allied to it in character, have been among the most obscure 

 subjects in Anatomy and Physiology ; and they are far from having 

 been yet fully elucidated. There seems sufficient evidence, however, 

 for regarding them in the light of appendages to the Absorbent 

 system, and as concerned, like it, in the process of Sanguification, or 

 the preparation of Blood. Hence this appears to be the most appro- 

 priate place for such a brief notice of them as the present state of our 

 knowledge admits. 



506. The Spleen is certainly to be regarded as an organ of compound 

 structure, having at least two sets of functions to fulfil. It is essen- 

 tially composed of a fibrous membrane, which constitutes its exterior 

 envelope, and which sends prolongations in all directions across its in- 

 terior, so as to divide it into a number of minute cavities of irregular 

 form, freely communicating with each other. In many animals, this 

 fibrous envelope, and the prolongations or trabeculce which it sends 

 through the substance of the organ, are distinctly muscular ; containing 

 a large proportion of the peculiar fusiform contractile cells formerly 

 described ( 337). These, however, do not present themselves in the 

 .Human spleen ; and its trabeculae do not appear to have any contractile 

 property. The areolse formed by the trabecular tissue, commonly 

 known as the splenic follicles, are differently occupied in different ani- 

 mals. In* the Ruminants they are lined by a continuation of the 

 splenic vein, which dilates into a cavernous structure, capable of re- 

 ceiving a very large quantity of blood. In Man, however, they have 

 no communication w r ith the splenic vein, and are chiefly occupied by 

 the Malpighian corpuscles and the parenchymatous tissue, which, in the 

 Ruminants, are limited to the partitions between the venous cells. The 

 Malpighian corpuscles of the spleen are whitish spherical bodies, which 

 are always connected with the smaller arteries, like currants with their 

 stalks ; being sometimes in immediate contact with them, but more 

 commonly being connected by a peduncle. Their size, when fully 

 formed, varies from l-3d to l-6th of a line. Each of them contains, 

 as its constant and essential elements, nucleated cells from l-4000th to 

 l-2500th of an inch in diameter, pale and faintly granular, together 

 with free nuclei, as well as larger cells of l-2000th of an inch in 

 diameter, which sometimes contain what appear to be red blood-cor- 

 puscles. These are enclosed in a capsule, which has no orifice, and 



