THE ANATOMY A BASIS OF STUDY 7 



centrally 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 animals showing superior speed, that the 

 nerves regulating the heart and lungs have greater power 

 than in the instance of those that are slower. Another 

 authorityt who has given this feature special study states 

 that the degree of contraction of the muscle is pro- 

 portioned to the degree of stimulation. This general 

 statement serves to sustain the position that the horse of 

 strong nervous organization has quicker and more com- 

 plete 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 tem- 

 perament expresses the fact by being a willing and 

 enduring worker in its sphere; while the horse of lym- 

 phatic temperament seemingly lacks zest in its labors for 

 the want of tone in its nervous system. The bilious tem- 

 perament reflects itself in a bad temper and springs chiefly 

 from the condition of the body; while the sanguine tem- 

 perament, 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 ner- 

 vous 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 ex- 

 pressed in work. 



*Mills, Comparative Physiology, page 213. 

 tSmith, Physiology of Animals, page 721. 



