34- 



proves the identity of that stimulus witli the one \vliich forms so im- 

 portant a part of the animal economy; an observation further illus- 

 trated by the fact that a pūrely mechanical stimulus, such as the ap- 

 plication of a needle, will excite muscular aciion after life has ceased. 

 If nioreover temperature, arterialization, digestion,&c., were all pro- 

 duced by electric agency, this would sūrely be manifested bydelicate 

 instrutnents ; but no such maiiifestation isobtained. Still further, it 

 is worthy of observation that in those animals (such as the Gijmnotus 

 electricus and the Torpedos) which are endowed with electric power, 

 a peculiar apparatus exists for the development of such power. On 

 the whole, indeed, it appears that modern ])hysiologists have scarcely 

 advanced in the explanation of the causes of animal temperature be- 

 yond that given by John Hunter, who says, " It is mostorobable that 

 it arises from some other principlej a i^rinciple so connected vvith life, 

 thatitcan, and does, act independently of sensation, circulation, and 

 volition ; and is that power which preserves and regulates the internal 

 machine. This povver of generating heat is in the highest perfection 

 when the body is in health ;" and the energy of the vital principle is, 

 in fact, the scale by which we can estimate the po\ver of the body 

 to sustain its temperature. 



There are many circumstances \vhich modify the effects of tempe- 

 rature upon animals and render them more susceptible of a lo\v tem- 

 perature. Such are want of exercise, inappropriate food, impure at- 

 mosphere, exhaustion vvhether from fatigue or hunger, immature age, 

 season, and the (juality of the air as to humidity or dryness. These 

 were severally considered. 



The excitement produced by exercise, the activity imparled by it 

 to the circulation, and the glovv vvhich it gives to the systeni, all tend 

 to render an animal less susceptible to the effect of a low tempera- 

 ture. Dens therefore in v/hich animals are kept should be of sufficient 

 size to allow of the taking of free exercise. Its importante is stronąly 

 illustrated by the fact that in very cold or elevated situations cessation 

 of motion is destruction, well known instances of which are the cases 

 of Sir Joseph Banks and Dr. Solander, and of Dr. Richardson. 



The quality of the food is of the greatest importance, and should 

 be regulated as nearly as possible in accordance vvith the habits of 

 the animals in a statė of nature. This subject requires therefore ex- 

 tensive inąuiry and observation. There is, however, one part of it 

 which is deserving of particular notice as connected with climate. 

 In the quality of his nourishment man is guided by the climate in 

 which he lives. The Esquimaux adopts a food entirely animal. The 

 Hindoo uses a diet solely vegetable, employing condiments only to 

 counteract the flatulency vvhich such food is likely to produce. The 

 inhabitants of northern countries take, and without material injury, 

 stimulating liquors ; — the use of such beverages is borne very badly 

 by the natives of India. In cold and elevated regions stimulating 

 diet appears therefore to be indicated, and it secms consecpiently ad- 

 visable to furnish such, including oven spirits or fcrmented liquors, to 

 tropical animals kept in our climate during the cold season. 



Air vitiated by respiration is deprived of the requisite stimulus to 



