267 



uole, llio protoplast would Ix' killed by being squeezed 

 between two masses of ice, when the vacuole expands on 

 freezing, lljin's experiments in which he succeeded 

 in keeping alive, by cautious slow freezing and thawing, 

 cells which otherwise would have l)een destroye«l give 

 much weight to his theory. 



IV. THEORY OF DEATH BY TOO RAriD THAWING 



For the investigators who maintain that cold, when 

 not accompanied by ice formation, is not generally lethal 

 and that freezing is usually a necessary condition for 

 death, the question arose as to whether death occurs dur- 

 ing freezing itself or during thawing. Almost all w^ho 

 favor the latter assumption think that it is the rapidity of 

 the thawing which renders it dangerous. So the theory 

 of ''death by thawing" and that of ''death by too rapid 

 thawing" will be treated together. 



The origin of the theory of "death by too rapid thaw- 

 ing" seems to be the old popular idea that, when a per- 

 son has frozen limbs, he should be warmed gradually. 

 This notion, frequent in the medical literature, is found 

 here and there also in the biological literature. For ex- 

 ample, Duhamel and Buff on (1737) say that when ani- 

 mals are frozen one puts them in snow, in water or in 

 dung to \varm them slowly. These authors also give as 

 a well-known fact that frozen fruit decays if thawed too 

 rapidly. They claim, furthermore, that they could save 

 plants (orange trees and geraniums) which w^ere coated 

 wath ice, by covering them so as to prevent a too rapid 

 thawing by the sun, or by exposing them to a slight 

 rain which also would cause a slow thawing. After refut- 

 ing the idea that the injurious action of the sun on frozen 

 trees might be due to a condensation of the rays by the 

 lenses constituted by the droplets of melting water, as 

 some have maintained, Duhamel and Buffon present the 

 following tentative hypothesis for explaining the mechan- 

 ism of action of rapid thawing : the vessels distended by 



