LESSONS IN HORSE JUDGING. 15 



^ quieten down. ' If the exercise or work be car- 

 ried to an extreme, then, as the muscular irrita- 

 hility is vanishing, pain in the muscles comes on, 

 which is nature's warning to stop the machine, 

 and lay in another store of irritability. 



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 othervdse 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 repeated, the parts would become heated 

 by friction were it not that this is provided 

 against. Friction is prevented by the tendon 

 being surrounded by a sheath, containing a lubri- 

 cating material called ^ joint oil' or technically, 

 'synovia.' This 'joint oil' or 'synovia' is gen- 

 erated by a membrane lining the * sheath,' and 

 which gets the name of 'synovial membrane,' 

 because it produces the synovia. 



Some muscles do not terminate in rope-shaped 

 tendons which have to ' play ' through lubricated 

 sheaths, but end in expanded sheet-hke tendons 

 which need no lubricating material. We shall 

 find that the muscles of the face are of the latter 

 description, and have their sheet-like tendons 

 closely connected to the skin over the lips. This 

 is well seen in ourselves in laughing. The bellies 



