457 



April 6, 1843. 



FRANCIS BAILY, Esq., V.P., in the Chair. 



Henry Wollaston Blake, Esq., and James Heygate, M.D., were 

 balloted for and duly elected Fellows of the Society. 



The following papers were read, viz. — 



1. " On the general and minute Structure of the Spleen in Man 

 and other Animals." By William Julian Evans, M.D. Communi- 

 cated by P. M. Roget, M.D., Sec. R.S, 



After adverting briefly to the discordant opinions of Malpighi, 

 Ruysch, and others regarding the structure of the spleen, the author 

 proceeds to detail the results of the investigations on this subject, in 

 which he has been for many years engaged. According to his ana- 

 lysis, the following are the component parts of this organ : — first, a 

 reticulated fibro-elastic tissue ; secondly, a pulpy parenchyma, con- 

 taining the Malpighian glands and the splenic corpuscles ; thirdly, 

 distinct cellular bodies ; fouiihly, the usual apparatus of arteries, 

 veins, lymphatics and nerves ; fifthly, certain fluids ; and lastly, the 

 membranes or tunics by which it is invested. 



He describes the cells of the spleen as being formed of a lining 

 membrane, continued from that of the splenic vein, and strengthened 

 by filaments of the fibro-elastic tissu.e. The splenic vein communi- 

 cates with these cells, at first by round foramina, then by extensive 

 slits resembling lacerations ; and it ultimately loses itself entirely in 

 the cells. The cells themselves communicate freely with one another, 

 and also with the veins of the parenchyma ; and may therefore be 

 considered as in some measure continuations of the veins. This 

 structure constitutes a multilocular reservoir of great extensibility, 

 and possessing great elastic contractility ; properties, however, which 

 exist in a much less degree in the human spleen than in that of her- 

 bivorous animals; in which animals the cellated structure itself is 

 much more conspicuous, and predominates over the parenchymatous 

 portion. As the splenic artery has no immediate communication 

 with the cells, these latter may be filled much more readily by in- 

 jection from the vein than from the artery. In the ordinary state 

 of the circulation, the blood, which has passed into the cells from the 

 veins, is pressed into the branches of the splenic veins by a force de- 

 rived from the elasticity of the fibro-elastic tissue which surrounds 

 the cavities of the cells, thus constituting a vis-a-tergo, which con- 

 tributes to propel the blood onwards in its jeirculation through the 

 liver. Should there arise, however, any obstructing cause which the 

 resilience of the spleen is unable to overcome, a regurgitation must 

 take place, leading to a congestion both in the mesenteric and splenic 

 veins. The spleen may thus serve as a receptacle for the blood of 

 the abdominal circulation during any temporary check to its free 

 passage into the vena cava; a purpose which is more fully answered 

 in herbivorous animals in whom the abdominal circulation is more 



