The mechanical restriction of respiration should not be overlooked. In European soldiers landed in India and marched in the tight woolen clothing and close stocks a high mortality has been induced and in horses with tight girths or collars and short bearing reins, and oxen working in collars a similar result is observed. Any condition of fever is a potent predisposing factor. Horses or cattle that are put to violent or continued exertion when too fat or out of condition are especially subject to sun-stroke. Fat cattle driven to market under a hot sun, or shipped by rail, crowded in a car and delayed on a siding under a hot sun, with no circulation of air, often have insolation in its most violent form. The same may be seen in the hot stockyard, with a still atmosphere and the fat animals subjected to the full blaze of a July sun. The chafed feet caused by travel, and the muscular weariness caused by standing in the moving car are material additions to the danger. Similarly horses suffer on the race track when subjected to protracted and severe work in hot weather, or again dragging loads in a heated street under a vertical sun, or on a side hill with the sun’s rays striking perpendicularly to its surface. A change in latitude has a decided effect, the Northern horse suffering much more frequently than the one which is native to the Southern States and which has inherited the habit of heat endurance. Finally faults in feeding and above all watering are appreciable factors. The privation of water in particular is to be dreaded. Tracy in his experience with American soldiers in Arizona, found that the command could usually be guarded against sun-stroke when a supply of water was kept on hand. It should be used guardedly, but nothing would act better in obviating an attack. On the other hand, when the canteens were empty, under the hot sun the seizures increased disastrously. Sheep are especially liable to suffer from heat by reason of their dense fleece, which hinders the evaporation of perspiration, and the cooling effect of air on the skin. When the temperature rises, respiration is accelerated and panting, the lungs seeking to supplement the work of the skin. When traveling in a heavy fleece, or in the hot sunshine in July or August sun-stroke is not uncommon among them. _Lesions._ Among the lesions may be named, vacuity of the left ventricle and fullness of the right ventricle and veins with fluid blood or a diffluent clot; congestion of the pia or dura mater, effusion into the ventricles, hæmorrhages into the subserous tissues, and degeneration of the muscles. _Symptoms._ =Horse.= When premonitory symptoms are observed the animal fails to respond to whip or voice, lessens his pace, stubs with his fore feet and sways with the hind, depresses his head and hangs heavily on the bit.