STRUCTURE OF THE SPLEEX. 753 



are seen included in a cell ; but more frequently the included blood-disks are 

 altered both in form and color. Besides these, numerous deep-red, or reddish- 

 yellow, or black corpuscles and crystals, either single or aggregated in masses, 

 are seen diffused throughout the pulp-substance: these, in chemical composi- 

 tion, are closely allied to the hsematin of the blood. 



Malpighian Corpuscles. On examining the cut surface of a healthy spleen, a 

 number of small semi-opaque bodies, of gelatinous consistence, are seen dis- 

 seminated throughout its substance; these are the splenic or Malpighian cor- 

 puscles (Fig. 415). They may be seen at all periods of life; but they are more 

 distinct in early than in adult life or old age; and they are much smaller in 

 man than in most mammalia. They are of a spherical or ovoid form, vary con- 

 siderably in size and number, and are of a semi-opaque whitish color. They are 

 appended to the sheaths of the smaller arteries and their branches, presenting a 

 resemblance to the buds of the moss rose. Each consists of a membranous cap- 

 sule, composed of fine pale fibres, which interlace in all directions. In man, 

 the capsule is homogeneous in structure, and formed by a prolongation from 

 the sheaths of the small arteries to which the corpuscles are attached. The 

 bloodvessels ramifying on the surface of the corpuscles, consist of the larger 

 ramifications of the arteries to which the sacculus is connected ; and also of a 

 delicate capillary plexus, similar to that surrounding the vesicles of other 

 glands. These vesicles have also a close relation with the veins (Fig. 416). 

 The latter vessels, which are of considerable size even at their origin, com- 

 mence on the surface of each vesicle throughout the whole of its circumference, 

 forming a dense mesh of veins, in which the Malpighian corpuscle is inclosed. 



Fig. 416. One of the Splenic Corpuscles, showing its Eelations with the Bloodvessels. 



It is probable that, from the blood contained in the capillary network, the 

 material is separated which is occasionally stored up in the cavity of the cor- 

 puscle ; the veins being so placed as to carry off, under certain conditions, those 

 contents to be discharged again into the circulation. Each capsule contains a 

 soft, white, semi-fluid substance, consisting of granular matter, nuclei similar to 

 those found in the pulp, and a few nucleated cells, the composition of which is 

 apparently albuminous. These bodies are very large after digestion is com- 

 48 



