NATURAL HISTORY. 21 



more particularly on account of the temperature of the air, every vege- 

 table having its proper temperature, and not being able to bear much 

 heat or cold beyond that point. They have their particular foods 1 , 

 which agrees much better with them than others : some are capable of 

 living on dry ground, others on moist ; some in clay, others in sand ; 

 some on stones, others in water. 



Perhaps vegetables have not the power of retaining either their 

 natural internal heat or cold, which is peculiar and proper for them, so 

 much as animals have. Animal heat varies but a degree or two from 

 the greatest external cold they can bear to the greatest heat. That 

 many animals can retain their heat in the greatest cold is verified in 

 the whale of Greenland. The frog is as cold in the hottest day in 

 summer as it is in the coldest day in winter 2 . 



Of the distinguishing Marks between Vegetables and Animals with 

 respect to Matter. 



Vegetable and animal matter contains the same materials, but dif- 

 ferently arranged and in different proportions. This is, in some degree, 

 proved by chemistry ; in some degree by putrefaction ; but most of all 

 by digestion. 



Chemistry is capable of decomposing, but only in progression, in 

 every stage of which a new combination takes place, which gives great 

 variety ; but no one ultimate is produced from a new combination of 

 the whole. 



There is so great a similarity between the vegetable and the animal 

 in many of their principles of life, that we should be apt to suppose 

 they were made up of the same composition of matter. There is 

 nothing in their structures that could induce us to suppose this ; but, 



1 [Here Hunter expresses an important truth; heedless apparently, or uncon- 

 scious, of its opposition to his previous statements respecting the all-sufficiency of 

 water alone as the food of plants, and his reasonings thereupon as to the essential 

 complexity of water ; such supposed nutritive power of water and the consequent 

 complexity of the fluid depending on the real nutritive particles contained in solu- 

 tion or fine suspension.] 



2 [This assertion neither tallies with some of Hunter's own experiments, nor with 

 any subsequent ones. In his paper entitled " Experiments and Observations on 

 Animals, with respect to the Power of producing Heat," Hunter writes : — "That 

 the imperfect animals will allow of a considerable variation in their temperature of 

 heat and cold, is proved by the following experiments. The thermometer being at 

 45°, the ball was introduced by the mouth into the stomach of a frog which had been 

 exposed to the same cold. It rose to 49°. I then placed the frog in an atmosphere 

 made warm by heated water, where I allowed it to stay twenty minutes ; and upon 

 introducing the thermometer into the stomach, it raised the quicksilver to 64°." — 

 Phil. Trans, vol. lxv. (1775).] 



