362 THE FLUIDS OF THE EGG. 



quantity in the ash of the white (0'49-jj-) as in that of the yolk, but 

 the peroxide of iron is present in smaller quantity (from 0'34 to 

 0'44-J), and so also are the lime and magnesia (there being L'j4$ 

 of the former and l*60f of the latter) ; while in the ash of the 

 yolk the earths are six or seven-fold increased, with a great 

 preponderance of the lime, there being 12 P 21 of lime and 2'07-g- of 

 magnesia. All these relations point to a determinate object in the 

 distribution of the inorganic matters amongst the cells and the 

 intercellular fluid of the animal body a point of view which we 

 shall find to be highly important in the consideration of the 

 history of development. 



We may readily convince ourselves of the presence of car- 

 bonates in the white of fresh eggs, by placing a little of this 

 substance under the microscope, and adding acetic acid ; we may 

 then often perceive an extraordinarily great development of gas. 

 The quantity of these pre-formed carbonates appears, however, to be 

 very variable, and is probably dependent on the longer or shorter 

 time during which the egg has been exposed to the air ; it is 

 possible that the carbonic acid obtained from the atmosphere may 

 abstract a portion of the base from the albuminate of soda. 



Free gases are contained both in the white and in the yolk, as 

 in all animal fluids. 



According to my analyses, fresh white of egg contains 12*274, 

 and the dried white 92*293^ of albumen (determined in accordance 

 with the rules laid down in vol. i., p. 339). We must refer 

 to vol. i., p. 335, for a notice of the difference between the 

 albumen of the egg and of the blood-serum. 



The white of egg is by no means free from fat, although this 

 substance is only present in extremely small quantity. On 

 examining fresh white of egg under the microscope, we discover 

 at intervals small granules, with three or four projecting teeth or 

 points, which are obviously composed of margarin. If further we 

 extract dried white of egg with ether, we sometimes, but not 

 always, obtain a light azure solution ; the fat which remains after 

 the evaporation of the ether consists of olein and margarin, but 

 also contains oleate and margarate of soda, if any alcohol has been 

 present in the ether which has been used : it is precipitated from 

 its alcoholic solution by acetate of lead ; when isolated and incine- 

 rated, it leaves an alkaline ash which effervesces with acids. 



We have already seen (in vol. i., p. 290) that the white of egg 

 ordinarily contains normal sugar ; from the determinations which 

 have hitherto been made, it appears that in the dry residue of 



