524 



been directed to the organism as a whole, with a view of determining 

 the question whether an animal apparently frozen to death could 

 be revived. The older writers* often allude to the revival of frozen 

 insects as a familiar fact. Rudolphif states that frozen Filariae are 

 brought to life upon thawing. Franklin found frozen fishes revive 

 on thawing; yet John Hunter J never succeeded in restoring the 

 animals he had frozen. 



One element of uncertainty in such experiments (in those on ver- 

 tebrate animals at least) is the difficulty of making sure that the 

 heart itself is frozen, without interfering with the expected result. 

 In the experiments of a later observer, Dumeril , it seems clear that 

 the hearts of the frogs he froze and recovered, were not frozen, 

 though the intestines were. 



Spallanzani || seems to have been the only one among the older 

 writers who studied the freezing of muscles removed from the influ- 

 ence of the general blood-current, and that only in an indirect way. 

 He revived irritability in the muscles of frogs, toads, and sala- 

 manders, which, after immersion for several hours in snow, had be- 

 come rigid, "presque gelees," and gave no contraction upon being 

 stimulated. But he states that muscles frozen by a more intense 

 cold lost their irritability for ever. His means of stimulation were 

 chiefly mechanical. There seems fair reason to suspect that the 

 muscles which recovered their irritability were but partially frozen, 

 had but partially lost their irritability, and would have exhibited a de- 

 cided contraction when treated by those modifications of the galvanic 

 stimulus which the modern physiologist has at his command. Spal- 

 lanzani^]", in another work, states that frozen snails died. 



Among later writers, the only authority I can find is Schiff, who 

 states**, "A sufficiently intense degree of cold will render muscles 

 rigid, and yet so that they can be revived. It is not clearly made 

 out though whether this is accompanied by any contraction." And 

 again, p. 46, " Frogs' muscles bear freezing without irretrievable loss 

 of irritability for a longer time than they will exposure to that 



* Reaumur, Whytt, Blumenbach, Spallanzani. 



f Histor. Entoz. t. ii. p. 62. 



J Works by Palmer, vol. iv. p. 131. 



Annales des Sciences Naturelles, 1852, vol. xvii. p. 7. 



|| Opuscules, tr. Senebier, vol. i. (ch. vi.) p. 113. 



^ Letters on Respiration. ** Lehrb. s. 44. 



