

CHAPTER VIII. 



BELATION OF ANIMAL BODIES TO HEAT, LIGHT, AND 

 ELECTRICITY. 



1. The relations which animal bodies have to heat, light, 

 and electricity, are highly interesting, and worthy of particu- 

 lar notice. vTo a certain extent, all animal bodies have the 

 power of regulating their own temperature! Many of them 

 develope electricity ; and some of them, like the lightning- 

 bug, and other insects, can produce light. These are singu- 

 lar properties of living animal matter. 



2. SThe heat of animal bodies is produced within them- 

 selves.; It is not received from without, nor can it be ; as 

 the natural temperature of the body is near 100 degrees ; 

 even when the temperature of the surrounding air is below 

 zero. How this is produced we shall inquire when we come 

 to treat especially of animal heat. 



3. Plants have a lower temperature than animals, and the 

 higher animals are in the scale of organized beings, so much 

 the more animal heat do they produce. Thus the tempera- 

 ture of what are called the cold-blooded animals, such as 

 fishes, 6s not much above that of the water in which they 

 live ; and Although they do not often freeze to death in the 

 winter, yet they become so torpid as to be incapable of mo- 

 tion. 



4. It is a favourite sport in New England in the winter 

 season, to hunt, -on skates, for the pickerel, and other fish, 

 which abound in the lakes and ponds ; and when found to 

 take them, by cutting through the ice with a hatchet ; and 

 to spear them by torchlight at night. Now had they the 

 faculty of producing animal heat, like quadrupeds, or birds, 

 or man, they would not be ^rendered torpid and incapable of 



>tion by cold. 



