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 ])arts 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 f 

 (Coelineus nigerl), 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 

 during the breeding-season, suggestive of a condition of surface favoiu-able 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 colour than usual. It was found like- 

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



♦ The efiect 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 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 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 difiFerence 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 immereion 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. 



t 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 ^^ of a grain ; it seemetl 

 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. 



