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THE CIRCULATION OF THE BLOOD 



brain and of the follicles of the mucous membrane of the intestines; among 

 the largest, those of the skin and especially those of the medulla of the bones. 



The form of the capillary network differs in the different organs of the 

 body, but is usually adjusted to the structural arrangement of the cells of 

 any given organ. 



The capillary network is closest in the lungs and in the choroid coat of 

 the eye. In the human liver the interspaces are of the same size, or even 



PIG. 148. Capillaries of Striated Muscular Tissue. From a cat. Magnified 300 diam- 

 eters. A, Artery; V, vein. (Heitzmann.) 



smaller than the capillary vessels themselves. In the human lung the spaces 

 are smaller than the vessels; in the human kidney and in the kidney of the 

 dog the diameter of the injected capillaries, compared with that of the inter- 

 spaces, is in the proportion of one to four, or one to three. The brain 

 receives a very large quantity of blood; but its capillaries are very minute 

 and are less numerous than in some other parts. In the mucous mem- 



