64 



"Secondly. — The Inferior Communicating Arteries, thirteen 

 or fourteen in number, proceed through the foramina in front 

 of the coffin-bone and supply the Circumflex Artery which en- 

 circles the toe of the os pedis and from which blood is usually 

 abstracted when a horse is bled in the foot. 



" From the Circumflex, proceed the Solar Arteries, thirteen or 

 fourteen in number, which, taking a radiated course towards 

 the centre of the foot, furnish the sensible sole with its requi- 

 site nourishment, and form the net-work of vessels from which 

 the horny sole is secreted." 



THE PLANTAR CAPILLARIES. 



An extremeiy interesting study is the capillary system, or cir- 

 culation. It is important to be acquainted with some of its 

 salient features ; as much so, indeed, as with the arterial and 

 venous systems of circulation. The great object of the capil- 

 lary circulation is to minister to the functions of secretion and 

 nutrition, as these operations can only be carried on while the 

 blood is in circulation. The term capillary is used to denote 

 all the minute vessels which pass between and connect the arter- 

 ies and veins. 



It has been estimated that the aggregate area of the cap- 

 illaries is eight hundred times larger than that of the arteries 

 which supply them. 



They are generally uniform in size, varying but a little in 

 different places. They are smallest in the brain, the lungs and 

 spinal cord, and largest in medullary matter, fat, etc. The 

 smallest are about 3,500th and the largest about i ( s 00 th of an inch 

 in diameter. They have but one coat, which is of a homoge- 

 neous character. They are nourished by imbibition. 



Their course is the same as the fibres of the tissues through 

 which they ramify. 



•They commence in arteries and terminate in veins. They 

 anastomose very frequently with each other, and form a net- 

 work of wonderful minuteness. 



