1823.] of the Egg during Incubation. 107 



to possess all the properties of the yellow oil existing in the yelk. 

 The yelk at this period, as before observed, has become more 

 fluid, and appears larger, and of a paler colour than natural. 

 Haller, indeed, asserts, that it has not increased in weight ; but 

 the above table renders the reverse very probable. These 

 appearances of the albumen and yelk have induced most obser- 

 vers to believe that an interchange of principles takes place 

 between them ; while others seem to have mistaken the yellow 

 modified albumen for the yelk itself. That an interchange of 

 principles has taken place, at least under the above circum- 

 stances, there can be no doubt ; yet the two are not indiscrimi- 

 nately mixed ; for when the egg has been previously boiled, tho 

 yelk, though softer than natural, is nevertheless rendered of a 

 firmer consistence than the modified albumen, and can thus be 

 readily separated from it ; there is, moreover, a distinct line of 

 demarcation between them, arising, apparently, from the proper 

 membrane of the yelk. Another argument in favour of the 

 opinion of the intermixture of the albumen and yelk at this 

 period, is derived from the following analyses of these constituent 

 principles of the egg ; from which it will be found that the quan- 

 tity of the saline matter is diminished in the albumen, and 

 increased in the yelk. It is a singular and striking fact, how- 

 ever, that although the oily matter of the yelk has made its way 

 to the albumen, very little of the phosphorus, which exists in such 

 large quantities in the yelk, has been removed with it." 



Unchanged albumen. 



Modified albumen, li- 

 quor amnii, animal, 

 membranes, &c. . . 



Yelk 



Sulphu- 

 ric acid. 



0-13 



0-08 

 0-09 



Phos- 

 phoric 

 acid. 



0-27 



0-38 

 4-03 



0-30 4-68 



Chlorine. 



0-19 



0-45 

 0-60 



1-24 



Potash, so- Lime, mag- 

 da, and nesia, and 



carb. 

 ditto. 



of 



1-03 



1-17 

 O80 



•00 



carb. 

 ditto. 



of 



0-18 



0T2 



0-68 



0-98 



The results of an analysis made on the 10th day of incubation, 

 show, that at this period " the proportion of phosphorus is 

 somewhat diminished in the yelk, and increased in the animal 

 and its appendages. The chlorine and alkaline principles seem 

 also to have diminished in the yelk and to have increased a 

 little in the albuminous portion." 



Experiments on the Egg at the End of the second Week, or 

 about the loth Day of Incubation. 



The egg has now lost, upon an average, about 130 grains in 



