302 THE UNFERTILISED EGG AS A [pt. hi 



various substances derived from the diet of the hen, and these, if 

 they are odorous or possess taste may very easily betray their presence 

 (e.g. the Swedish "Schareneier" described by Hansson). Table 23 

 gives the figures which are available for the nitrogen and Table 26 

 for the phosphorus distribution. These summaries bear out on a 

 detailed basis what has already been said. 



I -10. The Ash of the Avian Egg 



The ash of the yolk and the white of the hen's egg has been in- 

 vestigated by several workers, and a study of it reveals certain inter- 

 esting features. If Table 27 be examined, it will be seen that, in the 

 yolk as well as the white, potassium has almost invariably been found 

 to be present in greater amount than sodium. This is one of the 

 characteristics of the egg-cell, as will be seen later when the eggs of 

 other animals are considered. The yolk is also marked by the very 

 high percentage of phosphorus, most of which is, in accordance with 

 other evidence, in organic combination. The calcium is also mainly 

 in the yolk, as is the iron, but not the magnesium. If now the amounts 

 of metallic and acidic ion be calculated out in millimols and milli- 

 equivalents per cent, wet weight, it is found that in both yolk and 

 white there is an uneven balance, but while in the former case there 

 is much more anion than cation (anion/cation ratio above unity), in 

 the latter case the exact reverse holds, and the anion/cation ratio is 

 somewhat below unity, about 0-55. In the white, therefore, some of 

 the potassium and sodium must be combined with the proteins, as 

 ovoalbumenates, etc.* However, the excess of cation over anion in 

 the white is not so considerable as the excess of anion over cation 

 in the yolk, and, bearing in mind also the much higher percentage 

 of solid in the yolk than in the white, it would be expected that the 

 anion/cation ratio of the whole egg would be greater than unity, 

 and would approach that of the yolk. The facts show that this is, 

 indeed, the case, for the average anion/cation ratio calculated from 

 the results of all observers for the whole egg is 2-3, as against 2-8 

 for the yolk alone and 0-54 for the white alone. This was first noted 

 by Garpiaux. Forbes, Beegle & Mensching expressed it simply thus : 



Cubic centimetres normal solution 

 per 1 00 gm. dry weight egg 

 Total acid ... ... ... 120-28 



Total base ... ... ... 39*42 



Excess acid over base ... ... 8o'86 



* In both white and yolk, of course, the inorganic ash is basic. 



