CHAP. xxxv.J MALPIGHIAN CORPUSCULES. 515 



The splenic corpuscles are placed upon a small branch of the 

 arteries as upon a short peduncle or stalk, which sometimes con- 

 sists only of fibrous tissue, prolonged from the sheath of the 

 vessels, or they lie in the angle formed by the divergence of two 

 branches from each other. The artery divides into numerous 

 branches upon the surface of the Malpighian corpuscles. The 

 observations of Kolliker and Dr. Sanders, which have lately been 

 confirmed by Prof. Huxley, have shown that the substance of the 

 corpuscle itself is traversed by small capillary blood-vessels. These 

 small vessels probably pour their blood into small veins which 

 surround the corpuscle, and are of considerable size. According to 

 Mr. Gray, these veins receive the secretion of the Malpighian bodies. 



The Malpighian corpuscle does not appear to us to be invested 

 with a distinct and well-defined membranous capsule : but we are 

 inclined to agree with Kemak and Ley dig, who represent their 

 contents as not being separated by any distinct line of demarcation 

 from the splenic pulp, although the fibrous tissue derived from the 

 external wall of the vessels appears to form a sort of imperfect 

 capsule. The cells of which these bodies are composed readily 

 pass from them into the pulp. Mr. Gray has made the interesting 

 observation, that these bodies are very large, and well defined in 

 well-fed animals, and that, during the latter part of the digestive 

 process, they increase in size, while, in animals insufficiently fed, 

 they are very small, or absent altogether. In the latter, little in- 

 crease is noticed in their size after digestion. Their increase is con- 

 siderable under the influence of an albuminous diet; but when 

 animals are confined to fat or gelatine, these bodies are not to be 

 distinguished. 



Veins of the Spleen. The splenic vein is the largest branch of 

 the vena porta, and, like the others, is destitute of valves. The 

 branches into which the vein divides, do not communicate with 

 each other in the substance of the organ. Mr. Gray describes 

 three different modes in which the veins commence: 1. As con- 

 tinuations of the capillaries of the arteries, which is the most 

 common method ; 2. By inter-cellular spaces in the substance of 

 the spleen pulp through which the veins communicate with each 

 other. The smallest veins commence in this manner; or 3. By form- 

 ing an imperfect capsule to each Malpighian body. This latter mode 

 of commencement has not been described by other observers, and 

 Mr. Gray considers these small veins as the channels by which the 

 secretion of the Malpighian bodies is carried into the circulation. 



The vein ramifies abundantly upon the surface of the spleen, 



