INTRODUCTION. 5 



example, being «i condition, we mean that his 

 muscles are in good tone, or in other words, that 

 his muscles can lay in large quantities of irritability 

 which takes hours of hard toil to exhaust. The 

 process by which the muscles are brought to ' tone' 

 is called ' conditioning/ When large quantities of 

 this irritahility have been stored, the first ex- 

 penditure of it is intensely pleasurable, and this 

 pleasurable excitment, unrestrained, which it often 

 is on first coming out of the stable, is called 

 ' freshness.' Shortly, when some of the irritability 

 or freshness has gone off, further expenditure of 

 irritahility causes neither pleasure nor pain, but in- 

 difference, and the horse is said to ' quieten down.' 

 If the exercise or work be carried to an extreme^ 

 then, as the muscular irritahility is vanishing, pain 

 in the muscles comes on which is nature's warning 

 to stop the machine, and lay in another store of 

 irritahility, 



8. — The part of the muscle which contracts is its 

 red part, called its belly, (Fig. 1. 1 1) and the hard 

 white glistening continuation of the belly is called 

 the tendon (Fig. 1. 2 2). The belly of the muscle 

 is usually attached to the fixed part, while the 

 tendon is attached to the part to be moved. If, 

 however, the part otherwise to be moved is fixed, 

 and the muscle contracts, then the part to which 

 the belly of the muscle is attached has to move. 

 When the tendon is drawn towards the belly of 

 the muscle and the movements again and again 



