THE SENSITIVE SOLE. 429 



It is quite thick, and furnishes a bed for the numerous blood- 

 vessels entering and coming from the coffin-bone. The sensi- 

 tive lamellae are attached to it. It is an exceedingly elastic 

 substance, so much so, indeed, that it will stretch out and dfaw 

 back like India-rubber. In this resides the elasticity which 

 has been attributed to the lamellae. How much wiser is this 

 arrano-ement than to have the lamellae themselves endowed 

 with this high degree of elasticity, by which their union would 

 necessarily be endangered ! 



THE SENSITIVE SOLE. 



This is a tough, fibrous, and extremely vascular (full of 

 blood) membrane, firmly attached to the under side of the 

 coffin-bone, and corresponding in shape with the horny sole, and 

 lying on its upper, or convex, surface. 



It is chiefly composed of the same sort of fibrous, tough, 

 whitish, elastic (springy) substance which covers the upper, or 

 rounded, side of the coffin-bone, and to which the sensitive 

 lamellae are attached. It is more compact and finer than the 

 covering of the upper side of the coffin-bone. It forms the 

 bed for a beautiful net-work of veins, which furnish the blood 

 from which is secreted or formed the horny sole. Both the 

 fibrous and vascular parts are covered by a thin membrane, 

 from which pass many little tubes, or villi, entering the pores, 

 or little holes, on the upper side of the horny sole, and from 

 which it is secreted or formed, as has been before explained. 



The sensitive sole, sometimes called the fleshy sole, is united 

 around the lower border of the coffin-bone with the elastic 

 structure covering the bone. Behind, along the border of the 

 V-shaped cleft, it is united with the sensitive, or fleshy, frog. 

 Its thickness is, on an average, about the eighth of an inch, 

 though it varies in difterent parts, being the thickest toward 

 the heels. 



Its office, in part, is to prevent concussion, but chiefly to 

 furnish blood from which the horny sole is secreted, and to 



