164 



HISTOLOGY. 



trabeculae, some of them are thought to have free sensory endings. Lym- 

 phatic vessels are said to occur in the capsule and trabeculae, but not in 

 the pulp or nodules of the spleen . 



The spleen is a large organ, without obvious subdivisions. On its surface, 

 when fresh, there is a mottled effect due to areas bounded more or less definitely 

 by trabeculae. Such areas, about i mm. in diameter, have been described by 



~ x -_ Surface blackened by 

 precipitate of silver. 



Nerve branches 



for the arterial 



wall. 



-- Nerves of the pulp. 



Small nerv e _ 

 bundle. 



Branches for the 



arterial wall. ,*-'--' 



FIG. 184. GOLGI PREPARATION OP THE SPLEEN OP A MOUSE. X 85. 



The boundary between the spleen pulp and the lymphoid tissue is indicated by a dotted line. 

 The nerves are chiefly in the wall of an artery. 



Professor Mall as 'lobules' and he states that they "can easily be seen on the 

 surface of the organ or in sections." A lobule as he describes it, has a central 

 artery, and its base is where the lymphoid sheath of the artery terminates. There 

 are veins in the trabeculae, often three, at the periphery. A lobule is composed 

 of some ten structural (or histological) units, imperfectly separated from one 

 another by branches of the trabeculae. Each unit contains a central terminal 

 artery (branches of the lobular artery) and has peripheral veins (branches of 

 those about the lobule). Apparently, therefore, the lobules shown in the dia- 



