i6 STRUCTURES OF THE BODY. 



is much reduced in lenQ^th. The muscles of the loins and 

 back present the same character. In old age they are poorer 

 in red fibre, but richer in tendon." 



I may here mention that 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 sub- 

 stance ; connective 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 

 siofht of the marked differences which exist in the nervous 

 system of various animals, and which greatly heighten, or 

 may altogether nullify, advantages obtained from good con- 

 formation. We are aware, speaking within reasonable limits, 

 that the amount of contraction — i.e. force — exhibited by a 

 muscle is proportional 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 develop- 

 ment of muscle, may be perceptible. Not alone does the 

 amount of nervous force differ much among animals of the 

 same kind, but, also, some have the faculty of stimulating 

 their muscles by means of their nerves quicker than their 

 fellows can do. We see this well exemplified in adepts at 

 fencing, cricket, boxing, and other kindred sports ; at which, 

 so-called quickness of eye is all-essential. I may mention 

 that the brilliant bat, or accomplished maifre d amies, apart 

 from the possession of the necessary amount of knowledge. 



