TOADS FOUND INCLOSED IN ROCKS. 413 



thousands of years, are instances of vitality supported 

 under circumstances so abnormal as to excite the utmost 

 wonder at its tenacity. Such cases are manifestly 

 not asphyxia, and can hardly be said to be even coma. 

 The toad, as is well known to naturalists, is a foul- 

 blooded animal, and does not purify its blood perfectly 

 at the lungs during circulation. It seems capable, there- 

 fore, of living under similar circumstances to those under 

 which thick-leaved plants exist in hermetically-closed 

 conservatories without renewed air or water, and is able 

 sufficiently to purify the air around it for the purposes 

 of its own respiration. It can, therefore, live in a less 

 quantity of air, and with a less degree of absolute purity 

 in the atmosphere by which it is surrounded, than would 

 be possible for a pure-blooded animal, or one which, as 

 an essential of its health, required to purify its blood 

 perfectly at the lungs. But it is well known that the 

 toad possesses remarkable powers of vitality in the earlier 

 stages of its existence, i.e., when in the tadpole state, in 

 which, with gills like a fish, it may be seen in our slow 

 running streams and stagnant pools during the period of 

 its development as a small black comet-shaped creature, 

 consisting of a round nucleus or head, and a tail. In this 

 state, if separated from the head, the tail will continue 

 to live, and even grow for many days ; while, in the mean- 

 while, the head grows a new tail for itself, repairing the 

 injury and restoring the completeness of the animal. 

 But this power of vitality in animals, as well as in plants, 

 is in many instances more remarkable than the above. 

 In plants, as is well known, propagation by slips and off- 

 shoots is easily effected, and inversion of the whole 

 direction of vitality may be accomplished, for trees and 

 shrubs capable of being propagated by cuttings seem 

 generally to possess this remarkable peculiarity that 

 either end of the cutting may be inserted into the ground 



