INTRODUCTION. 11 



All animated matter has a teiideiicy and a desire for self-preservation. 

 But all living beings are liable to perish from disease or from accident. 



Pestilence is borne on the winds and on the waters. 



Judging from the animals themselves, they offer no sufficient data 

 enabling us to conjecture the duration of life. 



Though denied to entire genera, longevity may be granted to indi- 

 viduals. Among the lower orders, life is assuredly longer than usually 

 allotted to them by mankind. 



Several noted examples might be given. Of two Actinite, one sur- 

 vived twenty-two years in my possession, during which time it produced 

 above 300 young. The aspect of the other underwent an important 

 change, for the first time, during the fifteenth and sixteenth years of its 

 life in captivity. Neither of them could be less than thirty years old at 

 the period of these observations. Likewise the inhabitant of a minute 

 shell had survived nearly nine years, when it was destroyed by another 

 animal accidentally brought to its vicinity. 



Were not decay and death essential elements in the constitution of 

 the universe, it would plainly be rendered inadequate for the reception of 

 its multiplying inhabitants. 



Thus there is a continual waste and a constant replenishment. 



A suspension of the active and passive animal faculties, and of con- 

 scious existence, ensues in sleeji, and especially from that kind of it deno- 

 minated torpidity. 



The sleep of plants bears some analogy to the insensibility betrayed 

 by animals. 



Another kind of suspended animation, protracted even for years, 

 was discovered a considerable time ago, by a distinguished Italian natu- 

 ralist : and an eminent French physiologist has recently revived the sub- 

 ject by a learned treatise on the species of an entire genus endowed with 

 this remarkable property. Specimens removed from their native abode, 

 and allowed to dry, become motionless and insensible, and so they may 

 remain without extinction of life, until revived by humectation, after 

 the lapse of years. 



Humidity seems indispensable for demonstrations of the vital prin- 



