74 



ternal relations, by enabling it to receive and to convey impres- 

 sions of comparative degrees of safety or danger to the brain of 

 the system of which it forms a part, appears to me to be as neces- 

 sary as the special organization of the ear, the eye, and the 

 other organs of special sensation, designed for the fulfilment 

 of certain functions also in connection with the external rela- 

 tions of the animal. 



PRIMA FACIE REASONS. 



It appears to me that the impressions of safety or danger 

 could not so well be conveyed to the brain through the agency of 

 the eye alone as through the combined functions of the eye and 

 the foot. Actual contact of the foot with the ground, I take to 

 be a much safer criterion of safety or danger than a merely 

 visual estimate of those circumstances. Both faculties are in 

 perpetual exercise during locomotion ; that of sight to measure 

 distances, so as to place the foot with accuracy, whilst that of 

 touch receives the impressions of its good or bad qualities with 

 reference to safety or danger. 



I think these may be regarded, at least, as prima facie reasons 

 for the existence of a special endowment of sensibility in the 

 foot of the "noble quadruped." 



ANALOGICAL ARGUMENT. 



• 



The evidence in favor of this view derivable from analogy I 

 think, may fairly be adduced from the existence of this function 

 in that organ which is the homologue in man of the foot of the 

 horse — the organ of touch par excellance — the human hand. In 

 this the microscope enables it to be demonstrated that, be- 

 sides the sensation it possesses in common with the skin at all 

 other points, it is endowed with a larger supply of sensitive 

 nerve fibrillar at their extremities, where external objects are 

 felt, than elsewhere. Just at the points of contact with ex- 

 ternal objects sensibility is the most acute. 



