242 VIEWS, &C. PHYSIOGNOMY OF PLANTS. 



Ehrenberg, in his great work on Infusoria (p. 492 — 496), 

 has given the most complete history of all the observations 

 instituted on the so-called revivification of Rotifera. He 

 believes, that notwithstanding all the means of desiccation 

 employed, the organization-fluid still remains in the apparently 

 dead animal. He contests the hypothesis of "latent life"; 

 for death, he says, " is not life in a torpid state, but the 

 absence of life." 



The hybernation or winter-sleep of both warm and cold- 

 blooded animals, as dormice, marmots, sand-martins (Hirundo 

 riparia, according to Cuvier)* 4 , and of frogs and toads, 

 affords us evidence of the diminution, if not of the complete 

 suspension, of the organic functions. Frogs awakened 

 from their winter-sleep by warmth, can remain eight times 

 longer under water, without drowning, than frogs in the 

 breeding season. It seems as if the respiratory functions of 

 the lungs require a less degree of activity after the long 

 suspension of their excitability. The circumstance of the 

 sand-martin burying itself during the winter in marshes, is a 

 phenomenon which, while it scarcely admits of a doubt, 

 is the more remarkable, because in birds, the function 

 of respiration is so extremely energetic, that, according to 

 Lavoisier's experiments, two sparrows in an ordinary con- 

 dition will, in the same time, decompose as much atmospheric 

 air as a Guinea-pig. f Winter-sleep is not supposed to be 

 general to the whole species of these sand-martins, but only 

 to some few individuals. £ 



As in the frigid zone deprivation of warmth produces winter- 

 sleep in some animals, so in the torrid regions, within the 

 tropics, an analogous phenomenon is manifested that has not 

 hitherto been sufficiently regarded, and to which I have 

 applied the term summer-sleep. § Drought and a continuous 

 high temperature act like the cold of winter in reducing 

 excitability. Madagascar, excepting a very small portion of 

 its southern extremity, lies within the tropics, and here, 

 as was already observed by Bruguiere, the hedgehog-like 

 Tenrecs (Centeres, Illiger), one species of which (C ecau- 



* Regne animal, 1829, t. i. p. 396. 



f Lavoisier, Memoires de Chimie, t. i. p. 119. 



% Milne Edwards, Elements de Zoologie. 1831, p. 513. 



§ Relat. hist, t. ii. pp. 192, 626. 



