CIRCULATORY SYSTEM. 



SPLEEN. 



The spleen is a blood-forming organ, very vas- 

 cular, purple in color, and with a density slightly 

 more than that of the liver. It varies greatly in 

 size, the average being five inches long and three 

 inches wide. Its surfaces touch the left kidney, the 

 cardiac end of the stomach, and the left lower aspect 

 of the diaphragm. Its long axis follows the direction 

 of the tenth rib. It is practically covered by the 



Vein. 



Malpighian 

 corpuscle. 



Trabecula. 



Artery. 

 Spleen pulp. 



pig. 9 ^ Portion of section of human spleen. The figure gives a 

 general view of the structure of the spleen (Sobotta). 



peritoneum. The structures to be recognized are 

 capsule and trabecula, Malpighian corpuscles, and 

 spleen pulp. 



i. Capsule and Trabeculcz.^he investing peri- 

 toneum forms a serous coat with simple squamous 



