46 



foot of the horse, should differ so diametrically upon matters 

 that appear to be of the most simple and demonstrable char- 

 acter, as I think will be seen when we discuss the other functions 

 of the foot. 



THE SENSITIVE SOLE. 



Besides the laminal tissues, the periosteum of the coffin bone 

 furnishes a double membrane from its plantar surface to fulfill 

 similar functions for the horny and sensitive soles. Here, also, 

 proceeding from within outwards, we have the basal membrane 

 adherent to the bone, and a secreting membrane sending its 

 papillae into the internal surface of the horny sole, besides a 

 layer of elastic interperiosteal tissue coming between the two 

 layers of membrane last described — that is to say, it furnishes 

 a bed whereon the nerves, blood-vessels, and absorbents may 

 repose with safety, and yet suffer the necessary elongation and 

 shortening incidental to the movements of the foot without 

 injury ; and, being of the elastic variety of fibrous tissues, forms 

 the appropriate elastic medium, when its functions are unim- 

 peded, by which the natural springing and rebounding func- 

 tions claimed for the plantar cushion, for such it is, are effected. 



AN ERRONEOUS CONCEPTION EXPOSED. 



If the above description of the sensitive sole be correct, as I 

 deem it demonstrable that it is, by actual experiment, then 

 the common notion that the horny sole should be cut until it 

 springs or yields under the pressure of the thumb must be 

 founded upon an erroneous conception of the function of the 

 sole, no matter by whomsoever the doctrine may be taught, 

 since this practice neutralizes, to the extent to which it may be 

 followed, the action of the really elastic tissue within the foot, 

 and calls upon tissues that are not elastic to fulfill functions 

 for which they were neither designed nor adapted ; and, more- 

 over, endangers the vascular and filamentous connections of 

 the sensitive and the horny laminae, as well as those of the 

 sensitive and the horny sole, by causing a greater tension upon 

 those connections than they are able, or were intended to 

 bear. 



