chap, xxix.] THE SPLEEN. 227 



kinds of tissues : (a) the Malpighian corpuscles ; and 

 (b) the pulp tissue. 



297. The Malpighian corpuscles are masses 

 of adenoid tissue connected with the branches of the 

 splenic artery. Following the chief arterial trunks as 

 they pass in the big trabeculse towards the interior 

 of the spleen, they are seen to give off numerous 

 smaller branches to the spleen parenchyma ; these are 

 ensheathed in masses of adenoid tissue which are 

 either cylindrical or irregularly-shaped, and in some 

 places form oval or spherical enlargements. These 

 sheaths of adenoid tissue are traceable to the end of 

 an arterial branch ; and in the whole extent the 

 adenoid tissue or Malpighian corpuscle is supplied by 

 its artery with a network of capillary blood-vessels. 



298. The rest of the spleen parenchyma is made up 

 of the pulp. The matrix of this is a honeycombed, 

 spongy network of fibres and septa, which are the 

 processes and bodies of large, flattened, endotheloid 

 cells, each with an oval nucleus. In some, especially 

 young, animals, some of these cells are huge and 

 multinucleated. The spaces of the honeycombed tissue 

 are of different diameters, some not larger than a blood 

 corpuscle, others large enough to hold several. All 

 spaces form an intercommunicating system. The 

 spaces contain nucleated lymph corpuscles, more or 

 less connected with and derived from the cell plates 

 of the matrix. But they do not fill the spaces, so 

 that some room is left, large enough to allow blood 

 corpuscles to pass. 



The spaces of the honeycombed pulp matrix are in 

 communication, on the one hand, with the ends of the 

 capillary blood-vessels of the Malpighian corpuscles, 

 and, on the other, they open into the venous radicles 

 or sinuses (Fig. 132), which are oblong spaces lined 

 with a layer of more or less polyhedral endothelial cells. 

 These sinuses form networks, and lead into the large 



