349 
656. With respect to fishes, Spallanzani remarks. 
that, in great colds, they bury themselves in holes, 
and in the slimy beds of streams ; but never become 
absolutely lethargic *. Some tenches, which were 
placed in water five degrees below zero, continued 
to move although the water froze around them. In 
cold air they soon became immoveable, but instantly 
recovered action when replaced in water f. In these 
low temperatures, they breathed only seven times in 
a minute ; but as the temperature was increased, the 
respiration became accelerated. After a certain time, 
however, they died in vessels of frozen water from 
the want of fresh air t. A tench, kept during a 
whole night in air that was only half a degree above 
zero, consumed a small portion of its oxygen and 
formed carbonic acid ; which is a farther proof that 
they do not become entirely lethargic from cold. 
From these facts we learn, that fishes do not natural- 
ly become lethargic from cold, and therefore conti- 
nue always, in a small degree, to act upon the air. 
They lose, however, their former vivacity, and, in 
proportion as their respiration is suspended, they 
consume less oxygen gas ^]~. 
657. In the reptile class, the same author observed, 
that, in a temperature one degree and a half below 
zero, the heart in serpents beat only twice in a mi- 
nute, and respiration was suspended. When remo- 
ved to a temperature of 7% the heart soon recovered 
its action, and beat 1O or 12 times in a minute; and 
* Rapports, c. torn. i. p. 157. t ]{ji(J - P- Ii58 }6i ' 
: Ibid. p. l63. Ibid. p. l6"5, iGS. U Ibid. p. 18<J. 
