254 Royal Society. 



These results, so far as the particular instances are concerned, are 

 sufficiently confirmatory of M. Puget's ; and on my mind they leave 

 little doubt that his general proposition (his inference from his very 

 numerous experiments) is correct, that congelation is fatal to animal 

 life. It is hardly worth while to attempt to account for the different 

 conclusion I had come to (that referred to by him relative to the 

 leech), it being partly founded on the fact that leeches which had 

 been enveloped in ice for many days were not thereby killed, and 

 partly on witnessing some marks of vitality in leeches which were 

 believed to have been artificially frozen, and which very soon after 

 died. 



Whilst admitting that congelation, thorough congelation, of an 

 animal is incompatible with life, the cause of death from congelation 

 seems open to question, and more especially that assigned by M. 

 Puget as the vera causa — a change in the blood, and chiefly in its 

 corpuscles. That these corpuscles are changed by freezing in form 

 and condition seems to be certain. Before seeing M. Puget's paper 

 I had ascertained the fact, and not only that the corpuscles were 

 changed, but also that the entire blood was to some extent altered, 

 leading me at the time to ask whether some of the injurious effects 

 of frost-bite may not be mainly owing to the freezing of the blood 

 and the changes in consequence in the corpuscles and, in a less degree, 

 in the fibrin * ; and since, in examining the blood of the animals 

 exposed to the freezing-mixture, I have had this confirmed ; but the 

 change in these instances was comparatively slight ; even in those of 

 the congealed limbs of the frogs and toad the majority of the cor- 

 puscles appeared little altered ; some few seemed ruptured, some 

 corrugated, and more contracted. 



Judging from the effect of congelation on the heart of the frog 

 in experiment No. 5, and from the effects of congelation partially 

 produced, as in the extremities of the frog and toad, I would rather 

 attribute the death to the freezing of the organs, not excluding the 

 blood, than to the freezing of the blood alone ; and I would ask, is 

 not this view most in accordance with the pathology of the subject, 

 with all that we know of frost-bite and its consequences in man, and 

 with the results of Mr. Hunter's experiments on the local effects of 

 congelation in animals — those on the ear of the rabbit and wattle 

 of the cockf? and do not some even of M. Puget's results give it 

 support, such as the opacity of the crystalline lens, he admitting 

 that, were it possible for an animal to revive after complete congela- 

 tion, it would be blind from cataract ? Now, if the crystalline lens, 

 if the blood-corpuscles suffer and undergo an appreciable change 

 from congelation, it would be very remarkable indeed did not the 

 brain and nerves, and the organs generally, suffer from the same 

 cause, and experience changes incompatible with life. In the in- 

 stance of man, we know that a certain reduction of his temperature 



* Physiological Eesearches, 1863, p. 371. See also Trans. Eoyal Society of 

 Edinburgh, 1865, vol. xxiv. p. 26. 

 t Phil. Trans. 1778, p. 34. 



