SUSPENSION OF VITALITY IN ANIMALS. 257 



almost a lost art. The remedy lies, as has been said, in a return 

 to methods consecrated by glorious tradition, and fruitful of 

 results which, as experience has abundantly proved, can not be 

 attained by shorter or easier ways. Contemporary Review. 



[Concluded.] 



> 



SUSPENSION OF VITALITY IN ANIMALS. 



By M. VICTOE LAPOETE. 



FAMILIAR instances of suspended vitality, or rather latent 

 vitality, are afforded by seeds, which may be kept for years 

 without showing action, but are yet capable of being recalled to 

 the exercise of the functions of life. Other instances are afforded 

 by the lower organisms, which will remain dry and sterile for 

 indefinite periods, to be brought into full activity at any time by 

 supplying the due degree of moisture and warmth. Coming up 

 to higher forms of life, the same phenomena are usually mani- 

 fested in insects, one of the normal conditions of whose life the 

 nympha or chrysalis state is characterized by the exhibition of 

 the external appearance of death. During this stage the vital 

 processes are tempered down till only enough are in effect to 

 maintain a merely vegetative existence ; yet the insect is capable 

 of slight motions when subjected to a shock or pressure. The 

 duration of this apparent death varies according to the species 

 and to external conditions. There are species that require two 

 years of incubation before going through their metamorphosis. 

 Others pass to tlie perfect state in a few days. Butterflies demand 

 a certain degree of heat, below which they will not issue. The 

 opening of the chrysalis takes place naturally when these atmos- 

 pheric conditions are realized. If the season is late, the hatching 

 is also late. Hence we can prolong the duration of the chrysalis 

 state indefinitely by properly adjusting the temperature, delaying 

 to that extent the metamorphosis of the imprisoned mummy into 

 the free and winged insect. Reaumur, by putting chrysalides in 

 an ice-box, was able to keep them alive and retard their develop- 

 ment several years. 



" Perfect " insects are also capable of passing some time in a 

 more or less definite condition of apparent death without losing 

 the capacity to revive. I do not mean those simulations of death 

 which some species put on in order to escape their enemies, and 

 under which their condition may be mistaken by the most care- 

 ful and patient observer, but cases in which they revive under 

 really extraordinary conditions. Of such cases are instances of 

 flies, which, having been accidentally inclosed in casks of Madeira 



VOL. XXXVI. 17 



