THE NERVOUS SYSTEM. ^^ 



The component parts of the body which, respectively, 

 have the same structure, are called tissues. Thus we 

 have bony tissue, consisting of bone ; muscular tissue, 

 of muscle ; nervous tissue, of nerve substance ; con- 

 nective tissue, of white fibrous material ; and so on. 



The Nervous System. — While considering the form 

 of the horse from a mechanical point of view, we must 

 not lose sight of the marked differences which exist in 

 the nervous system of various animals, and which greatly 

 heighten, or may altogether nulhfy, advantages obtained 

 from good conformation. We are aware, speaking within 

 reasonable limits, that the amount of contraction — i.e., 

 force — exhibited by a muscle is proportionate to the degree 

 of stimulation given by its nerves. As the nervous system 

 of some animals acts far more energetically than that of 

 others, it follows that the former, other things being equal, 

 will be stronger than the latter ; although no difference 

 in conformation, or in development of muscle, may be 

 perceptible. Not only does the amount of nervous force 

 differ much among animals of the same kind ; but some 

 individuals of the same species can stimulate their muscles 

 b}' means of their nerves quicker than their fellows. We 

 see this well exemphfied in adepts at fencing, cricket, 

 boxing, and other kindred sports ; at which, so-called 

 quickness of eye is all essential. The brilliant batsman or 

 accomplished mattre d' amies, apart from the possession 

 of the necessary amount of knowledge, judgment, and 

 physique, excels because he has the gift of moving his 

 muscles, in response to the stimulus received by the nerves 

 of his eyes, quicker, as well as in more accurately regulated 

 style, than ordinary men. This assertion is in no way 

 based on mere theory ; for we find that among men whose 

 duty it is to record (as in observatories) the exact moment 

 at which they see certain phenomena occur, it is necessary, 

 in order to avoid error, to allow for the difference in 

 time these men, respectively, take ; although it may 



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