THE SPLEEN. 14! 



lie, at varying intervals, elongated, curved, spindle- 

 shaped, and flattened endothelial cells, which have 

 their long axes parallel with the axes of the canal. 

 These veins, whose walls, as will be seen, are not 

 closed but fenestrated, are in direct communication 

 with the spaces which are still left in the meshes of 

 the pulp-cords by the cells which incompletely fill 

 them. 



Still another point remains to be considered, 

 namely, the course of the blood after its exit from 

 the above-described fine arterial twigs on which the 

 Malpighian bodies are formed, until it enters the 

 fenestrated cavernous veins of the pulp. The 

 opinion of different observers on this point differs 

 somewhat, owing to the extreme technical difficul- 

 ties in the investigation ; but it seems probable that 

 after passing out of the fine arterial twigs, through 

 the intervention of the capillaries it is poured direct- 

 ly into the meshes of the pulp-cords, and that after 

 circulating here around the cells, without distinctly 

 walled channels, it finally finds its way through their 

 fenestrated walls into the cavernous veins, whence 

 it passes out of the organ through the large efferent 

 veins at the hilus. 



TECHNIQUE. 



Sections of Uninjected Spleen, a. Cat. A general 

 view of the arrangement of the different structures of the 

 spleen may be obtained from very thin sections of a cat's 

 spleen hardened in dichromate of potassium and alco- 



