DIVISIONS OF THE ANIMAL KINGDOM. XXI 



earth, to remain in their state of slumber till the return of the 

 warmer season shall call them again into life. And other mi- 

 gratory birds, as the cuckoo and the corn- rail, are sometimes 

 overtaken by this sleep of winter before they have been able 

 to make their periodical flight, during which they may be 

 tossed about without their moving a joint of the body. 



The lower tribes of animals, whose sensations are obtuse, 

 present examples yet more striking than the higher tribes of 

 the power of the living principle to preserve the animal organ- 

 ism from the action of external agents. Many species will 

 survive the most cruel torments, and revive after a long 

 period of seeming death. Certain species of vibrio have been 

 so dessicated by the sun that they have become like dust, 

 and, after twenty years, have been restored to life by sprink- 

 ling them with a little water. 



Of the power of the living body to resist those agents 

 which would otherwise act upon and decompose it, an ex- 

 ample is furnished by a substance, the production of the 

 body itself. The gastric juice is secreted from the interior 

 of the stomach, and is employed to dissolve the food which is 

 received into the alimentary canal. This substance possesses 

 a prodigious solvent power, yet it never acts upon the living 

 organs with which it comes into contact in the body, although 

 capable of dissolving all animal matters when deprived of 

 life. Numerous parasitic creatures are formed to live in the 

 stomachs of other animals. When alive they resist all the 

 actions of the powerful solvent by which they are surrounded, 

 but the moment life is extinct in them, they become subject 

 to its powers, and undergo decomposition. 



Examples, too, of the property of bodies having life to 

 resist those agents which would destroy them in their dead 

 state, may be everywhere drawn from the vegetable king- 

 dom. All the hardier forest trees resist the intensest cold 

 of the climates where they are naturalized, and the vegetable 

 juices remain without being frozen. Every perfect seed con- 

 tains within itself an embryo plant, which only requires the 



