232 ANIMAL HEAT. 



spring ; to 104 in summer ; to be at 82 when the air was at 40 ; 

 arid at 73 in winter. 



The same tendency in vegetables is shown by the greater dif- 

 ficulty with which the juices in their stems and branches are 

 frozen than lifeless fluids ; by ice thawing when roots shoot into 

 it l ; and by snow upon the leaves or stems of plants thawing 

 sooner than that which lies on surrounding inanimate bodies. 

 J. Hunter observed a branch of growing fir and a bean leaf thaw 

 the part of the surface of a freezing mixture on which it was 

 placed, and the fir subsequently another to which it was removed." 1 

 When the sheath of the arum maculatum and cordifolium is burst- 

 ing, and the cylindrical body just peeping forth, it is said, by 

 Sennebier, to be so hot for some hours as to seem burning n ; and 

 twelve of them placed round the bulb of a thermometer to have 

 raised the mercury from 79 to 143. 



Even eggs are cooled and frozen with more difficulty than equal 

 masses of inanimate matter ; although, when once frozen and 

 their life destroyed, they freeze readily. 



" This natural temperature in man is so constant, equable P, 

 and perpetual, that, excepting slight differences from variety of 

 constitution, it varies but a few degrees in the coldest climate and 

 under the torrid zone. For the opinion of Boerhaave, that man 

 cannot live in a temperature exceeding his own, has been refuted, 

 since the admirable observations q of H. Ellis, the celebrated 

 traveller, and formerly the governor of Georgia, by the remarkable 

 experiments r of many excellent physiologists." 8 Dr, Fordyce, 



1 American Medical and Philosophical Register, vol. iii. p. 19. 1814. 



m Phil. Trans., 1775. 



n An Introduction to Physiological and Systematic Botany. By Sir J. E. Smith, 

 M.D. p. 92. 



1 J. Hunter, 1. c. p. 79. 



P " J; B. Van Mons, Journal de Physique, t. Ixviii. 1809, p. 121." 



i " Philos. Trans, vol. i. p. ii. 1758. 



Arn. Duntze had previously made the observation in regard to brutes. Expert 

 calorem animalem specfantia. Lugd. Bat. ] 754, 4to. 



Consult also Benj. Franklin, Experiments and Observations on Electricity. 

 Lond. 1769, 4to. p. 365." 



T " Duhamel and Tillet, Mtm. de VAcad. des Scienc. de Paris, 1704. 



Blagden and Dobson, Philos. Trans. 1775." 



s " The heat of the weather, even in Europe, occasionally exceeds our natural 

 temperature. This was the case on the 3d of August, 1783, at noon, when I 

 was on the Lucerne Alps, in company with the excellent Schnyder of Wartensee. 



