XIX] THE SPLEEN 151 



the veins ; they are devoid of any proper muscular 

 and connective tissue coats; in the centre of the section 

 large trabeculae cut transversely or obliquely will pro- 

 bably be seen containing both arteries and veins; if 

 the section passes through the point of entrance of the 

 vessels these will be seen running towards the centre 

 surrounded by tissue continuous with the capsule. 



The splenic pulp occupying the spaces of the 

 trabecular network ; it resembles somewhat the folli- 

 cular substance of the lymphatic glands but has a 

 mottled appearance; in it are roundish masses of 

 tissue, the Malpighian corpuscles, more deeply 

 stained than the splenic pulp: when the corpuscle is 

 cut transversely to the artery which it surrounds, the 

 artery will be seen to be near one side (all the small 

 arteries in the pulp are surrounded by a variable 

 amount of lymphoid tissue). 



Examine the splenic pulp under a high power and 

 note that the mottled appearance is due to the presence 

 of red blood corpuscles scattered irregularly in it. (These 

 are stained yellow with picric acid and orange with 

 eosin.) 



2. Thin section of a dog's spleen, washed out by 

 injection. Stain as in 1. Observe (h. p.) 



There are no distinct lymph-channels like those in 

 the lymphatic glands. 



The reticulum of the splenic pulp varies in appear- 

 ance ; in places it appears as a network of cells having 

 in various directions flange-like projections which taper 

 off and join with the similar processes of neighbouring 

 cells ; elsewhere the cells may be nearly or wholly 



