12 LESSONS IN HORSE JUDGING. 



to the levers of the body, and move them, in doing 

 so always act in one and the same way — namely, 

 by alternately lengthening and shortening. Of 

 these two movements, one is active, the other 

 passive. It is the active movement, that of short- 

 ening, which does the work. After a muscle has 

 shortened, or, as it is termed, contracted, it allows 

 other forces to pull it out or lengthen, it and it 

 passively submits to being so lengthened. 



6. — All muscles are made up of countless bun- 

 dles, and these bmidles are made up in fibres. 

 These fibres being about the same size of all cases, 

 it follows that the more of them the stronger will 

 be the muscle, hence the larger the muscle the 

 stronger. A muscle fibre (See Fig. 1. CD) is made 

 up of a number of squares, placed one on the other, 

 as you would place a pile of dice. These squares, 

 on being stimulated, change their shape, as seen 

 in the diagram. The power of changing their 

 shape is called muscular irritability, and resides 

 somehow or other in the muscle itself, or, in other 

 words, every fibre has irritability. This irrita- 

 hility is called forth when a stimulant is applied. 

 Various stimulants wiU caU it forth. If you see 

 an animal that is newly kiUed and which has its 

 skin removed, you see the flesh twitch or quiver 

 in various parts. This is the contraction or twitch- 

 ing here and there of the muscles, whose irrita- 

 bility is affected by the cold air, the cold air act- 

 ing as a stimulant. If you now pinch one of the 

 muscles, or prick it wHh a pin, it will quiver or 

 contract. The same would occur if you applied 

 galvanism to it. 



