252 Royal Society :— 
mixture was made of pounded ice and common salt ; the temperature 
by it was commonly reduced to below 10° Fahr., or at times so low 
as 2° or 3°. The results obtained were briefly the following :— 
1. A leech was exposed to the mixture in a small glass tube just 
large enough to hold it, using the tube for stirring the mixture, 
Taken out when perfectly rigid and hard, and gradually thawed, 
it showed when punctured a faint indication of irritability ; there 
was a just perceptible contraction of the part punctured, the oral 
extremity, and nowhere else. It did not revive. 
2. Another leech was similarly exposed, but for a shorter time. 
When divided by an incision, it was found not frozen throughout. 
When punctured, it showed marks of irritability in a slight degree 
stronger than the preceding: it soon died. 
3. Two leeches were similarly treated at home, and for a some- 
what longer time, the temperature reduced to 3°. These, when 
gradually thawed, one exposed to the air, the other left in the mix- 
ture, showed no marks of revival; but they retained a certain elas- 
ticity, so that when bent they shortly recovered their former attitude, 
after a manner somewhat resembling a vital movement; but inas- 
much as they did not respond by the slightest contraction to punc- 
ture, it may be inferred that the movement was not vital. They 
resisted putrefaction for many days. 
4. A frog in a thin glass vessel was kept in the mixture about a 
quarter of an hour. It was very rigid when taken out ; thawed, no 
part, on puncture, afforded any indications of life; watched two or 
three hours, it proved to be dead. 
5. The heart of a frog, removed immediately after decapitation, 
whilst still pulsating, was subjected to the freezing-mixture in a 
small glass tube. After having been frozen, on thawing it remained 
motionless, even when punctured. It had been kept in the mixture 
only a few minutes. 
6. The inferior extremities of a frog kept extended by a bandage 
and thus introduced into a glass tube, were submerged in the mixture, 
the body of the frog being held in the warm hand; taken out after 
some minutes they were quite hard and motionless, whilst the body 
and upper extremities did not appear to be affected. It moved 
about, dragging the lower extremities as if they were dead. In about 
four hours it recovered the use of its femoral muscles, on the fol- 
lowing day the use of the muscles of the legs; the day after, it was 
able to bend and extend these limbs ; but there was no proof that its 
feet had recovered sensibility. On the fourth day it was found dead. 
7. The lower extremities of a large toad were immersed in direct 
contact with the mixture, the temperature falling to 3°. Gradually 
thawed, the parts showed no marks of life. This toad, which before 
the trial was in a dull state, afterward became almost torpid, and so 
continued until the following morning, when it was apparently dead : 
opened, the auricles were found feebly acting, ceasing after a few 
seconds*. 
* This toad was a female which had shed her ova; the oviduct was still large ; 
the stomach was distended with caterpillars, slugs, &c., seeming to show that 
