CHAP. XXXV.] SPLENIC ARTERY. 513 



Mr. Gray has shown that many of the capillary vessels are not 

 directly continuous with the veins, but that the blood, in passing 

 from one set of vessels to the other, traverses intercellular spaces 

 in the spleen pulp. The veins also, in many cases, appear to com- 

 mence in intercellular spaces, so that it is not difficult to conceive 

 how the contents of the vessels extravasate into, and become 

 mixed with, the constituents of the pulp, especially when the organ 

 is distended with blood. These changes appear also to take place 

 to a more limited extent within the veins themselves. Although 

 this may be the correct explanation of the manner in which the cells 

 in the pulp communicate with the blood in the vessels, we cannot 

 look upon it by any means as demonstrative. 



Splenic Artery. The splenic artery is the largest branch of the 

 cseliac axis, and the size of this vessel in proportion to the organ to 



Fig. 248. 



Transverse section of the human spleen, showing the mode of distribution of the arteries, 

 and the manner in which their sheaths are formed. After Mr. H. Gray. 



which it is distributed, is considerably larger than that of other 

 glands, with the exception of the thyroid. The large size of the 

 vessel would lead to the inference that more arterial blood is 

 distributed to the spleen than is required for the mere purposes of 

 nutrition. The branches of the artery are invested with sheaths 

 derived from and continuous with the fibrous capsule of the organ, 

 and they have a similar structure to it. Each arterial branch is distri- 

 buted to a particular part of the organ, and it does not anastomose 

 with contiguous branches. The smaller arteries, about the - 2 -Jo of 

 an inch in diameter, are connected with the Malpighian bodies, 

 which are usually placed in the points of bifurcation of the vessel. 



