Dr. J. Davy on the Congelation of Animals. 253 
8. A similar experiment was made on the lower extremities of an 
active frog, and with a similar result, except that the vivacity of the 
animal was for a short time but little impaired: after four hours it 
was apparently dead; opened, its auricles contracted when punc- 
tured. It may be right to mention that, before exposing the toad 
and frog to the freezing-mixture in direct contact, it was ascertained 
that the frog bore the immersion of its lower extremities in a satu- 
rated solution of common salt without any apparent loss of sensibility 
or motive power*. 
9. The lower extremities of an active frog of a large size were 
wrapped in tin-foil, and, together with one of its upper extremities not 
so wrapped, were kept in a freezing-mixture about a quarter of an 
hour. The frozen parts in thawing showed no marks of life. The 
frog died in about three hours. 
10. A cockroach, a flesh-fly, and a minute insect, an ichneumon + 
(Ceelineus niger’), confined together in a small glass tube, were kept 
some minutes in the mixture. Thawed, they were found all three 
dead. 
there was no diseased state. It is noteworthy that the apertures of the cutaneous 
glands appeared to be closed; for when the animal was irritated, there was no 
ejection of the acrid fluid, a circumstance I had before noticed in a female 
durimg the breeding-season, suggestive of a condition of surface favourable to 
the male in the generative act. When the tubercles were incised, they were 
found to contain the acrid fluid in plenty, and, judging from its bitter taste 
and the ixritating effects of an extremely small portion applied to the tongue, 
not deficient in activity. “Ihe same state of the cuticular glands was found in 
another female toad killed by congelation, which had shed few of its ova,—this 
on the 23rd of June. It was of a lighter colour than usual. It was found like- 
wise in two examined in July, in which some ova remained. 
* The effect of immersion of the lower extremities of a frog in a saturated 
solution of common salt varies, I find, according to the length of time; if 
for a very few minutes, it is inconsiderable; if for many, it is well marked ; 
and if much prolonged, it is fatal. In one instance, after a quarter of an hour’s 
immersion, the limbs seemed paralyzed, the animal in a state approaching to 
torpor: after having been well washed in fresh water it slowly recovered its 
activity, and the limbs their motive power and sensibility,—their motive power 
first, their sensibility later—indeed not until the followig morning, judging 
from the effects of puncture. After a longer immersion, with a fatal result, the 
limbs had become rigid and somewhat hard, especially the feet, as if their 
juices had been extracted by osmotic action. Opened after three hours, even 
the auricles were motionless, and this when punctured. The muscles of the 
limbs no longer showed a striated structure, whilst those of the upper extremi- 
ties displayed this structure distinctly. 
The toad, with a thicker skin, was found to bear the immersion of its extremi- 
ties for a longer time; but the difference seemed to be only in degree; much 
longer continued, the same effects were produced, viz. rigidity, with loss of mo- 
tion and sensibility, which (the immersion not being too long) were slowly 
recovered after freshwater ablution. 
The blood-corpuscles, acted on by the same solution, underwent a change, 
contracting slightly, and acquiring a granular appearance, commencing in their 
nuclei. 
+ For the name of this insect I am indebted to Dr. Gray, F.R.S. It was se- 
lected on account of its minuteness : it weighed hardly 54, of a grain ; it seemed 
probable, on account of the minuteness of its vessels, that its fluids might escape 
congelation, after the manner of fluids in capillary tubes, which may be reduced 
many degrees in temperature without being frozen. 
