THE LUNGS. 
261 
obvious that a more ample supply of uncontaminated blood 
will be required to sustain the energies of life, and violent 
action of the muscles forces the blood more rapidly through 
the veins, and hence the quick and deep breathing of the 
animal when running at speed. Therefore, the more capa¬ 
cious the chest, the greater will be the supply of pure blood, 
as the lungs will have more room to expand and perform 
the functions which we have above described. Besides, a 
capacious chest will fit him for a longer duration of speed. 
Those who are accustomed to hunting or horse-racing, 
must have frequently witnessed the wonderful relief which 
loosening the girths have afforded to a horse after a severe 
gallop. The tightening being removed, permits the chest to 
expand and contract to a greater extent, and consequently 
yields a larger portion of purified blood. A very short rest 
will sufficiently manifest how much the exhausted energies 
of those organs will recover when the greater expenditure 
is not necessary. 
Even for animals which are not required to possess speed, 
such as cart, waggon, dray, and farmers’ horses, a capacious 
chest is equally necessary ; for this reason, that in these 
there is generally a great accumulation of both flesh and 
fat which require a large portion of the blood to supply his 
growth; consequently large and ample chests are requisite 
so as tc afford room for the necessary provision of a rapid 
purification of the-contaminated blood. 
Diseases of the lungs are among the worst to which 
horses are liable, and most frequent of occurrence, and 
hence the most likely to impair his usefulness. A horse 
labouring under diseased lungs is unfit for any service, nor 
can all the art of the ablest veterinary surgeon produce 
even a semblance of alleviation, and hence is too frequently 
unjustly considered as unskilful. In other complaints, such 
