118 THE SUMMERING OF HUNTERS. 



form stout uiiNielding arms of levers ; the muscles 

 are the powers which move these arms of levers, 

 and the nerves transmit the current which sets in 

 motion the muscles. The bones form joints by ex- 

 panding their substance at the part where the joint 

 comes ; then the ends of the bones which form a 

 joint and which press upon each other are covered 

 with a rubber-like substance called cartilage, which 

 acts as a buffer, and lessens shock from conpussion ; 

 then again, oil has to be supplied to lubricate the 

 inner surfaces of the joints to prevent friction. The 

 muscles, in getting attached to the bones which 

 they have to move, have to do so by an intermediate 

 substance called tendon, and, as muscles move 

 bones by alternately lengthening and shortening the 

 tendons have to glide up and down through sheaths 

 which are lined by a surface which secretes oil or as 

 it is called synovia. We see then that we have two 

 sets of oiling apparatus — one set to oil the joints, 

 and another set to oil the tendons. It is this ap- 

 paratus which gets out of order so largely during 

 the hunting season and gives trouble in the form of 

 windgall, thorough-pin, bog-spavin, &c., all names for 

 precisely the same condition, affecting the same struc- 

 ture, only at different parts of the animal machine. 



We will now proceed to enumerate the four heads 

 already mentioned :— 



1. — Throioing the Horse out of Condition. — This 

 is extremely easy to do, because the same qualities 



