THE FARMER AT HOME. 345 



broken out afresh, and even fractures have been disunited in states of 

 great general debility. 



REPTILES. Reptiles are distinguised from birds and quadrupeds 

 by their cold blood and single heart, that is, with only one ventricle, 

 and from fish by their respiring through lungs. Their blood is never 

 at a much higher temperature than that of the medium in which they 

 live. No other animals are capable of enduring so great extremes of 

 heat and cold as the reptiles, especially some particular species. 

 Frogs, for instance, have continued to live in the human stomach, 

 and in lumps of ice. From the peculiar structure of their bodies, 

 they are able to suspend their respiration for a considerable time, and 

 are also endowed with the faculty of enduring an abstinence that 

 would prove fatal to warm-blooded animals. Most of them can live 

 in the air as well as in water. Many live indifferently in either ele- 

 ment. Some pass a certain period of life, or certain seasons of the 

 year, in one, and the rest in the other ; and some, finally, are confined 

 to the water, or to the land. They live chiefly in morasses, swamps, 

 and stagnant waters, damp, dark places, caves, and holes in the 

 earth. 



As means of defence, nature has given to some of them great 

 bodily strength, or sharp teeth, as to the crocodile ; to others a deadly 

 poison, as to certain kinds of serpents ; to others, a hard covering, as 

 to the tortoise ; to many, a disgusting smell, or an acrid humor, which 

 they eject. Some of them have a remarkable power of reproduction, 

 by which they renew parts of the body of which they have been de- 

 prived. Some can live for an incredibly long time without air, and 

 even without food, and some undergo transformations like insects. 

 None of them chew their food, but they swallow it whole, and digest 

 it at leisure. They are in general extremely tenacious of life, and 

 will continue to move, and perform their animal functions, even after 

 the severest injuries. Their colors and general appearance are, in 

 most instances, disagreeable ; some, however, are decorated with 

 the most vivid coloring. Their voices are either harsh and grating, 

 or they are entirely dumb. Most reptiles are oviparous. In some, 

 particularly in the frosts, the eggs are not fecundated until after their 

 expulsion from the female ; hence they are merely provided with a 

 thin membranous covering. The eggs of others, as the tortoise's, have 

 a soft, tough skin, resembling parchment, while, in other genera, the 

 eggs are furnished with a hard, calcareous shell. In those species 

 which are viparous, the eggs are regularly formed, but are hatched 

 internally, as in vipers. 



RESIN. From the various species of pine, there exudes a balsam 

 which concretes in the form of tears. It differs somewhat according 

 to the peculiar tree from which it is obtained, and by distillation it is 

 separated into two distinct ingredients ; oil of turpentine, which is 

 volatile, and resin, which is not. If a quantity of pine wool is col- 

 15* 



