54 THEORY OF EXERCISE. 



from fatigue, than a horse in hard condition would do ; on 

 account of the comparative inactivity of his powers of 

 excretion. Lymphangitis and azoturia are diseases which 

 are closely connected with want of exercise. 



Muscular development " is due in part to the growth of the 

 pre-existing fibres, and in part to the formation of new fibres " 

 (Halliburton). 



Owing to the fact that horses when in a state of nature 

 spend a considerable, if not the greater, part of the twenty- 

 four hours in movement, their limbs cannot bear long 

 enforced idleness without becoming more or less unsound. 

 Hence we find that stabled horses which have too little 

 exercise are liable to get swelled legs, especially behind ; 

 because the hind legs being farther from the heart than the 

 fore ones, the circulation of blood in them is more torpid. 

 Also, from want of pressure, the growth of the frog becomes 

 diminished, and consequently its secreting membrane becomes 

 liable to inflammation, which is made manifest by thrush. The 

 habit of standing on cold stones appears to be a not un- 

 frequent predisposing cause of navicular disease. Long 

 continued standing, as on board ship (p. 371), is a fertile exciter 

 of laminitis (fever of the feet). It seems probable that this 

 variety of laminitis is set up by waste nitrogenous material 

 (pp. 56, 122 and 123), the deposition of which would be 

 favoured by the slowness of the circulation in the feet of an 

 unexercised horse, and by their coldness. 



As the tissues can utilise the nutritive materials which they 

 receive from the blood only at a slow rate ; exercise for both 

 health and development should be long continued during the 

 day, and from day to day. 



REST. 



As the energy (p. 10) expended by the body, even during 

 slow walking, is greater than that obtained from the blood in 



