400 THE EXTERIOR OF THE HORSE. 



so to speak, establish its individuality, and which, in the species, also 

 concur in endowing it with those faculties which constitute the blood. 



Definition and Nature of the "Blood." This being laid 

 down, we are in a position of giving having the same opinion upon 

 this point as Messrs. Sanson * and Baron 2 the anatomo-physiological 

 interpretation of the metaphysical conception of the word blood, which 

 until now had scarcely been understood but as the expression of a 

 distinct force, an immaterial essence, isolated from and independent of 

 the body which it governed. 



If it can be said of man that he is an intelligence served by 

 organs, with better reason may it be added of the horse that he is a 

 nervous system served also by instruments, generators of force and of 

 speed. Without the nervous organism the latter are nothing ; without 

 them it is reduced to the most utter powerlessness ; with them it is 

 everything. These two parts of the living being are indispensable to 

 each other for action ; the nervous system could not command if its 

 servants did not obey and act. Now, every command, in order to be 

 heeded and carried out, supposes an agreement and a previous under- 

 standing between those who are intrusted with its exercise. It sup- 

 poses, moreover, a veritable correlation of action between the agents 

 which command the action and those which execute it. In the same 

 manner in the organism, if there is a harmonious concord between the 

 different parts (the spinal cord and the brain) of the central nervous 

 system which presides over the action of the organs (between the 

 powers whose function it is to properly direct the machine), if, besides, 

 there is a correlation between the nervous system and the organs them- 

 selves upon which it depends (between the directing powers of the 

 machine and its machinery), there will result a kind of all-pervading 

 and regulating harmony, a perfect equilibrium between those pieces of 

 the economy and the forces which set them in action. 



It is to this state of equilibrium the result of a perfect nervous 

 system, considered with regard to its functional activity or its dynamic 

 intervention that the name blood is given. 



But in what especially does this perfection consist? In the in- 

 tensity of the reflex power, that is to say, in the property which the 

 nerve-centres possess of transforming more or less quickly the im- 

 pressions which they receive from the external world through the 

 intervention of the senses into motor reactions. 



1 A. Sanson, Trait<5 de zootechnie, 2e 6d., t. iii. p. 197. 



2 R. Baron, La Dynamom6trie biologique, in Archives vtrinaires, ann6e 1877, p. 705. 



