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. Itis 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 ut 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 cock+? 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 Researches, 1863, p. 371. See also Trans. Royal Society of 
Edinburgh, 1865, vol. xxiv. p. 26. 
7 Phil. Trans. 1778, p. 34. 
