I)r. Davy on the Congelation of Animals, 



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 fol- 

 lowing morning, when it was apparently dead : opened, the auricles were 

 found feebly acting, ceasing after a few seconds*. 



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 punctured. 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 saturated solution of common salt without any appa- 

 rent loss of sensibility or motive power f. 



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. 



* This toad was a female which had shed her ova ; the oviduct was stiil large ; the 

 stomach was distended with caterpillars, slugs, &c., seeming to show that 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 during the breeding-season, sug- 

 gestive 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 irritating effects of an extremely small portion 

 applied to the tongue, not deficient in activity. The 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 coloiu* than usual. It was found like- 

 wise in two examined in July, in which some ova remained. 



t The effect of immersion of the lower extremities of a frog in a satm'ated 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 pro- 

 longed it is fatal. In one instance, alter 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 ; the motive power first, their sensibility later ; indeed not until 

 the following 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 extremities 

 displayed this structure distinctly. 



The toad with a thicker skin was found to bear the immersion of its extremities for 

 a longer time; but the difference seemed to be only in degree; much longer con- 

 tinued, the same effects were produced, viz. rigidity, with loss of motion and sensibility, 

 which (the immersion not being too long) were slowly recovered after fresh water 

 ablution. 



The blood-corpuscles, acted on by the same solution, imderwent a change, contract- 

 ing slightly, and acquiring a granular appearance, commencing in their nuclei. 



