HORSESHOEING. 



43 



Fig. 26. 





After the arterial or pure blood passes through the capil- 

 laries it is collected bj the veins, to be returned to the heart ; 

 then it is driven to the lungs for purification, and is again re- 

 turned to the heart, from, 

 whence it is pumped through 

 the arteries to all parts of 

 the body. 



The veins are more 

 numerous than the arteries ; 

 they have thinner walls, 

 and the larger ones are pro- 

 vided mth valves tliat pre- 

 vent the impure blood from 

 flowing backward. The 

 veins carry impure or dark- 

 red blood towards the heart, 

 and if one is opened the 

 dark blood flows in a steady 

 stream; it does not spurt. 

 The great number of vein- 

 lets in the lower parts of 

 the foot form a complex 

 net- work (plexus) of ves- 

 sels which are in such mani- 

 fold and close union with 

 one another that checking 

 the flow of blood in one part 



J . • 1 • /• ^°°* viewed from below and behind: a, digital 



does not seriously mteriere arteries;. c, arteries of the plantar cushion; /'", 



,„:+'U 4-1, „ /!„ : „J? 4.1, small branches of the semilunar artery of the os 



With the flowing 0± the pedis, which ramify in the velvety tissue of the 



blood towards the larger sole;yl,digitalvein;B, venous plexus of the heels 



^ or bulbs; D, solar venous plexus; G, circumflex 



veins. The following are vein of the toe; 3, posterior digital branch of the 



. . plantar nerve; 4, cutaneous branches of the same. 



the most important of these 



net-works of veins or venous plexuses : ( 1 ) the solar venous 

 plexus (Fig. 26, D) : (2) the podophj/Uous venous plexus (Fig. 

 25, C) ; (3) superficial coronary venous plexus (Fig. 25, B) ; 



