Hitman Physiology. 



207 



cheeks they enlarge, so as to carry red globules, and give the 

 glow of healthy blood to the face. 



Fig. 49 gives an idea of the distribution of the venous capil- 

 laries and veins, gradually uniting into larger and larger trunks, 

 and so gathering the blood and carrying it back to the heart. 



The distribution of arteries and veins to the extremities is 

 beautifully shown in Fig. 50, where the arteries, generally 

 lying deeper, and better protected than the veins, can be seen 

 branching off to the thumb and ringers; while the interlacing 

 veins flow back nearer the surface. Perhaps the mode in 

 which arteries and veins are distributed in their minutest 

 ramifications has not been better shown than in Fig. 51, 

 copied from a preparation of Sir Astley Cooper, of the injected 

 arteries and veins which enclose a villus of the intestines, 

 magnified 45 diameters. 



Fig. 50. CIRCULATION OF THE Fig. 51. ARTERIES ANL 

 HAND. VEINS OF AN INTESTINAL 



VILLUS, magnified 45 dia- 

 meters: arteries dark. 



Small as are the minute blood-vessels and capillaries, the 

 blood rushes through them with great freedom and rapidity. 



