THE CIRCULATION. 



capillary network is most dense, such as the lungs (fig. 50), 

 most glands, and mucous membranes, and the cutis. The 

 meshes of this kind of network are not quite circular, 

 but more or less angular, sometimes presenting a nearly 

 regular quadrangular or polygonal form, but being more 

 frequently irregular. The capillary network with elon- 

 gated meshes (fig. 5 1 ) is observed in parts in which the 



Fig. 50.* 



Fig. 



vessels are arranged among bundles of fine tubes or fibres, 

 as in muscles and nerves. In such parts, the meshes 

 usually have the form of a parallelogram, the short sides of 

 which may be from three to eight or ten times less than the 

 long ones ; the long sides always corresponding to the axis 

 of the fibre or tube, by which it is placed. The appearance 

 of both the rounded and elongated meshes is much varied 

 according as the vessels composing them have a straight 

 or tortuous form. Sometimes the capillaries have a looped 



* Fig. 50. Net- work of capillary vessels of the air cells of the horse's 

 lung, magnified, a, a, capillaries proceeding from b, b, terminal branches 

 of the pulmonary artery (after Frey). 



f Fig. 51. Injected capillary vessels of muscle, seen with a low 

 magnifying power (Sharpey). 



