COMPOSITION OF EGGS. 247 



to include all the substances which the tissues of the 

 growing animal need for their nutrition, and which are 

 required for the production of animal heat. 



The yelk and albumen of eggs are in the same relation 

 as food for the embryoes of oviparous animals, that milk is 

 to the young of Mammalia, and afford another example of 

 mixed food being provided as the most perfect nutrition. 



COMPOSITION OF FOWLS' EGGS. 



White. Yelk. 



"Water . . . 80*0 . . -5373 



Albumen . . . 15-5 . . . . 17-47 



Mucus . . 4-5 Yellow Oil . 2875 



Salts . . . . 4-0 . . . . 6'o 



Experiments illustrating the same principle have been 

 performed by Magendie and others. Dogs were fed ex- 

 clusively on sugar and distilled water. During the first 

 seven or eight days they were brisk and active, and took 

 their food and drink as usual ; but in the course of the 

 second week, they began to get thin, although their appe- 

 tite continued good, and they took daily between six and 

 eight ounces of sugar. The emaciation increased during 

 the third week, and they became feeble, and lost their 

 activity and appetite. At the same time an ulcer formed 

 on each cornea, followed by an escape of the humours of 

 the eye : this took place in repeated experiments. The 

 animals still continued to eat three or four ounces of sugar 

 daily ; but became at length so feeble as to be incapable of 

 motion, and died on a day varying from the thirty-first to 

 the thirty-fourth. On dissection, their bodies presented all 

 the appearances produced by death from starvation ; in- 

 deed, dogs will live almost the same length of time without 

 any food at all. 



When dogs were fed exclusively on gum, results almost 

 similar to the above ensued. When they were kept on 

 olive-oil and water, all the phenomena produced were the 

 same, except that no ulceration of the cornea took place : 



