268 AMERICAN AGRICULTURE. 



perspiration. The latter are almost destitute of clothing, 

 and subsist on their light juicy tropical fruits, which contain 

 scarcely 12 per cent, of carbon, yet furnish all the elements 

 for abundant perspiration ; the latter are imbedded in furs, 

 and devour gallons of train oil or its equivalent of fat, which 

 contains nearly 80 per cent, of carbon, that is burnt up in 

 respiration to maintain a necessary warmth. The bear 

 retires to his den in the beginning of winter, loaded with fat, 

 which he has accumulated from the rich, oily mast abound- 

 ing in the woods in autumn. There he lies for months, 

 snugly coiled and perfectly dormant ; the thickness of his 

 shaggy coat, his dry bed of leaves and well protected den 

 effectually guarding him from cold, which in addition to his 

 want of exercise, draw slightly upon respiration to keep up 

 the vital heat. When the stores of carbon and hydrogen 

 contained in the fat are expended, his hunger and cold com. 

 pel him to leave his winter quarters, again to wander in 

 pursuit of food. Many of the swallow tribes in like man- 

 ner, hybernate in large hollow trees, and for months eke out 

 a torpid, scarcely perceptible existence, independent of food. 

 Activity and full respiration on the return of spring, demand 

 a support which is furnished in the myriads of flies they daily 

 consume. The toad and frog have repeatedly been found in 

 a torpid state, embedded in lime-stones, sand-stones and the 

 breccias, where they were probably imprisoned for thou- 

 sands of years without a morsel of food ; yet when exposed 

 to the warmth of the vital air and the stimulus of its oxygen, 

 they have manifested all the activity of their species. This 

 they are enabled to sustain only by an enormous consump- 

 tion of insects. Dr. Play fair states, that in an experiment 

 made by Lord Ducie, 100 sheep were placed in a shed, and 

 ate 20 pounds of Swedes turneps each per day ; another 100 

 \\ ere placed in the open air, and ate 25 pounds per day; yet 

 the former, which had one-fifth less food, weighed, after a 

 few weeks, three pounds more nor hend than the latter. He 

 then led five sheep in the open air between the 21st Novem- 

 ber and 1st December. They consumed tH) pounds of food 

 per day, the temperature being at 44 degrees; and at the 

 end of this time they weighed two pounds less than when 

 first exposed. Five sheep were then placed under a shed, 

 and allowed to run about in a temperature of 49 degrees. At 

 first they consumed 82 pounds per day ; then 70 pounds, 

 and at the end of the time they had gained 23 pounds. 



