THE ANATOMY A BASIS OF STUDY 7 



by the brain and from there it is carried to all parts of the 

 body by the spinal cord through the main channel of the 

 vertebrae, and from this it branches out to stimulate many 

 muscles. The stimulation for action must come from the 

 nerve centers and these consequently have much to do with 

 the quickness and the strength with which a horse may act. 

 It has been determined * in the races of dogs and other ani- 

 mals showing superior speed, that the nerves regulating the 

 heart and lungs have greater power than in the instance of 

 those that are slower. Another authority f who has given 

 this feature special study states that the degree of contraction 

 of the muscle is proportioned to the degree of stimulation. 

 This general statement serves to sustain the position that the 

 horse of strong nervous organization has quicker and more 

 complete control over its muscles than the one deficient in 

 this feature. 



4. Temperaments. To the nervous organization, its tone 

 and force, we can largely trace the temperaments that are 

 characteristic of horses. The horse of nervous temperament 

 expresses the fact by being a willing and enduring worker in 

 its sphere; while the horse of lymphatic temperament seem- 

 ingly lacks zest in its labors for the want of tone in its nerv- 

 ous system. The bilious temperament reflects itself in a bad 

 temper and springs chiefly from the condition of the body; 

 while the sanguine temperament, resulting from apparently 

 opposite conditions, finds expression in a disposition that is 

 kind and willing. In this connection it should be stated that 

 the term nervous temperament is not used in the sense in 

 which it is commonly accepted, namely, a lack of nervous 

 control; for such a condition usually results in an irritable 

 and erratic temperament which is devoid of results as 

 expressed in work. 



* Mills, Comparative Physiology, page 213. 

 t Smith, Physiology of Animals, page 721. 



