GRADING EGGS 455 
According to Gautier we have the following: 
Percentage. 
Water... cc ccc ee cee eee eee nee ees 47 .19-51.49 
10) Ce (a 48 .51-42 81 
Fats (olein, palmitin, and stearin).................. 21.30-22 . 84 
Vitellin and other albumins........................ 15.63-15.76 
Lecithins.. 0... cece eee cece eee ne ees 8.43-10.72 
Cholesterin.. 0... 0. eee ee eee eee ee 0.44— 1.75 
Cerebrin. . 0... cee ccc ce eee eee eee enna aes 0.30 
Mineral salts... 0... cc ce ec ee eee ee ees 3.338- 0.36 
Coloring matter | 
Glucose | cee ete tenes eee ee eenes eae ee eee 0,553 
Poleck and Weber also give the following as the analysis of the min- 
eral salts of the yolk: 
Percentage 
Sodium (NaeO)... 0... ccc ce cece tn ene n eens 5.12- 6.57 
Potassium (KeO).. 0... ce tenes 8.05- 8.93 
Caletum (CaQ). 0... ccc ce cet ence ene nes 12. 21-13. 28 
Magnesium (MgO)........ 0.00. cece cnet een e eens 2.07— 2.11 
Tron (Fe2O3).. 0... ccc eee eee eee eens 1.19- 1.45 
Phosphoric acid, free (P203)........ 0... ee eee eee 5.72 
Phosphoric acid, combined... 1.0.0... 2... ce eee ee eee 63 . 81-66 .70 
Silicie acid (Si02). 6. eee ee ee eens 0.55- 1.40 
Chlorine... 0... ec ce en eect erent eens Traces 
According to Simon, the shell is made up of an organic matrix of the 
nature of keratin. This matrix is largely impregnated with lime salts. 
The pigments of the shell are said to be derived from the common 
pigment of blood. The shell membranes are also composed largely of 
keratin, with a small amount of mineral salts, principally calcium phos- 
phate. The white of the egg is supposed to consist of compartments 
which are divided by thin membranes and which contain the liquid 
albumen. ‘These membranes are continuous with the chalaze and the 
shell membranes. The yolk consists largely of spherical cells, most of 
which are filled with fat. 
The bacteriology of eggs has received considerable attention and 
much interesting and useful data are available. As far as is known 
eggs have not been important in spreading pathogenic bacteria. 
Grading of Eggs. This is essentially a commercial problem. Under 
some conditions, the grading of eggs is very difficult. However, in 
practice they are graded by the candling process and observations with 
