508 DR DAVY ON THE FREEZING OF THE EGG OF THE COMMON FOWL. 



7. On the night of the 9th of March, two eggs were exposed to the open sky, 

 one newly laid, the other from lime-water. The thermometer close to them fell 

 as low as 20°. At 8-30 a.m., the following morning it had risen to 31°. There 

 had been a fall of snow, and the eggs were found buried in the snow, as was also 

 a glass of water, the water about equal in volume to that of an egg ; the water 

 was frozen to the depth of about an inch. Both eggs were found fractured longi- 

 tudinally. The newly laid egg was easily cut in two by a knife, both the albumen 

 and yolk being comparatively soft. The former had a crystalline appearance, 

 and was of a light-yellow colour. The yolk was marked with concentric lines 

 of different hues of yellow and orange, the latter most conspicuous towards the 

 centre. The thermometer at the centre was 305° ; next the yolk in the albumen 

 it was 29*5°. The two parts not being firmly frozen were easily separated. The 

 egg from lime-water was as easily divided. Its albumen exhibited much the same 

 appearance as that of the newly laid. Its yolk was of an orange colour at centre, 

 but not concentrically marked, like that of the preceding. Its temperature at the 

 centre was 30°, that of the albumen, close by the yolk, was 29 75°. The newly 

 laid egg was somewhat the largest, its long diameter being about ^th of an inch 

 in excess of that of the other ; their shorter diameter was the same. 



Besides the preceding, I have made other trials on change of temperature of 

 the two kinds of eggs ; the newly laid, and those long kept in lime-water. This 

 was done by putting them alternately into hot and cold water, accompanied by 

 others of the same kind which had been boiled hard. I have observed no diifer- 

 ence in the rate of increase and diminution of temperature, except a slight one, 

 and that, as well as I could judge, depending on the difference of the weight 

 of the eggs used. Even between the eggs hardened by boiling and those not 

 so hardened, the augmentation and increase of temperature hardly appreciably 

 differed.* 



or membrane next the shell, was highly vascular, as was also the vitelline membrane, their vessels 

 conveying red blood of a florid hue. The red corpuscles were, for the most part, of the form of those 

 of the adult fowl ; some were circular and yet nucleated ; these were of a larger size. The fluid be- 

 tween the allantois and the yolk was slightly coloured reddish, from blood corpuscles suspended in 

 it, from the rupture of some vessels. It was limpid, very dilute, contained little or no albumen. 

 Wben heated to the boiling point, it was not coagulated, nor did it become even milky, merely a minute 

 portion of greyish matter subsided, no more than might be referred to the blood corpuscles. It had 

 a strong alkaline reaction. 28-2 grs. of it, evaporated to dryness, left only -3 gr. of solid matter, 

 or 1-06 per cent., consisting chiefly of common salt and an alkaline carbonate. Contiguous to the 

 yolk, and contained within its vascular membrane, there was some very tenacious transparent albu- 

 men, of faint alkaline reaction. By heat it was coagulated ; the coagulum was milk-white, unusually 

 dense and firm. 57 g'l's. of the viscid matter, evaporated to dryness, afforded a residue of 14-7, or 25'8 

 per cent. The yolk consisted of a thin and thicker fluid, both of which showed a faint alkaline reaction. 

 A mixture of the two was of the sp. gr. 1022 ; of the thin kind, 339 grs., evaporated to dryness, 

 were reduced to 8'6 grs., or 25*3 per cent, of the thicker kind; 30-4 grs. evaporated to dryness were 

 reduced to 9'3, or 306 per cent. The eyes of this foetus were fully formed ; the lens of each, resting 

 on the crystalline humour, was '133 of an inch in diameter, a perfectly transparent sphere. 



* The appearance of the yolk of the newly laid egg, and of that from lime-water, kept about 

 twelve months after being boiled, slightly differed ; that of the latter was of a paler and less bright 



