PROD UCTION OF HE A T IN COLD-BLOODED ANIMALS. 849 



Consecutive Periods of Thirty Minutes. 



THE PRODUCTION OF HEAT IN COLD-BLOODED ANIMALS. 



One of the most characteristic phenomena of life is an exchange of material, 

 an oxidation which results in the production of heat. In the lowest forms of 

 life, both vegetable and animal, a certain amount of heat is produced. 

 Numerous experiments have shown that this is so, although, owing to the 

 cooling effect of evaporation from the surface of the body, the heat produced 

 may be masked by the excessive loss ; the temperature of a frog may be 

 lower than that of the air, notwithstanding that the animal is constantly 

 producing heat. 



It is unnecessary to give here an account of the temperature of plants, 1 

 but, in addition to the facts already stated, 2 further details must be brought 

 forward concerning the production of heat in the lower animals. Hunter 3 

 found that the temperature of earth-worms, slugs, and leeches might be a degree 

 above that of their surroundings ; a carp had a temperature of 20 '6, a viper 

 one of 20, when that of the surroundings was 18 '6 and 14*4 respectively. 



In bees, even in winter, the capacity for producing heat has already been 

 shown to be very great. Next in point of interest is the fact, to which 

 attention was first drawn by Valenciennes, 4 that pythons, when coiled 

 round their eggs during incubation, maintain a temperature even 20 

 above that of the surrounding air. The following are some of the results 

 obtained by Sclater, 5 who compared the temperature of a female python with 

 that of the non-incubating male, which was kept in the same compartment of 

 the reptile house : 



1 See on this subject Dutrochet, Ann. d. sc. nat., Paris (Botanique) 1840, SeV. 2, tome 

 xiii. pp. 5 and 65 ; Gavarret, " De la chaleur produite par les etres vivants," Paris, 1855, 

 p. 516; Sachs, "Physiology of Plants," p. 404 ; Vines, "Physiology of Plants" ; Van 

 Tieghem, "Traite de botanique," Paris, 1891, tome i. It is interesting to notice that an 

 abnormal rise of temperature, fever in fact, has been observed in the tissues around a 

 wound in a plant. Annals of Botany, 1897. 



2 This article, p. 792. 



3 "Works," Palmer's edition, London, 1837, vol. iv. p. 131 et seq. 



4 Compt. rend. Acad. d. sc., Paris, 1841, tome xiii. p. 126. 



5 Proc. Zool. Soc. London, 1862, p. 365. 



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