THE STRUCTURE OF THE SPLEEN. 115 



The spleen is met with only in vertebrate animals, and in 

 them its presence is nearly constant. The whitish rounded 

 corpuscles of Malpighi, which are found in many animals and 

 occasionally in man, and are visible to the naked eye in tlye red 

 substance of the spleen, were described by Dupuytren and 

 Assolant as greyish bodies, without any cavity in their interior, one- 

 fifth of a line in diameter, and so soft as to take the liquid form 

 when raised on the knife. More recent observations have shown 

 them to be vesicles, and not solid bodies containing an albumin- 

 ous fluid. They appear to be appended in groups of six or 

 eight to an arterial ramuscule. 



Miiller considers them as growths or processes connected 

 with the sheaths with which the capillary branches of the 

 splenic artery are provided. Of their intimate texture and uses 

 nothing is positively known. They are supposed to belong to 

 the absorbent system and to consist of dilatations of the absorb- 

 ent vessels. 



The pulpy substance of the spleen consists of a mass of red- 

 brown granules, as large as the red particles of the blood, but 

 differing from them in form, being very irregularly globular. 

 These granules are easily separable from each other, and in 

 their midst the minute arteries ramify in tufts, and terminate in 

 the plexus of venous canals, in which all the blood of the spleen 

 is poured, before it is carried out of the organ by the splenic 

 vein. There are no distinct cells in the spleen ; those spaces 

 seen in sections of the organs which have been mistaken for 

 cells, are divided venous canals exceedingly thin and delicate. 

 When the spleen is inflated with air, these vessels are distended 

 and assume a slightly cellular appearance. 



The spleen is now generally considered as belonging to the 

 class of erectile or distensible tissues, and to serve as a diver- 

 ticulum or temporary outlet to the blood, which accumulates 

 in the venous plexuses of the stomach during digestion, and also 

 when the blood is hurried so rapidly through the system as in 

 running, as to endanger some of the weaker vessels ; in the latter 

 case the accumulation is usually attended, especially in young 

 persons, with pain in the region of the spleen. Its uses in the 



