ACCURACY IN COMMERCIAL GRADING OF OPENED EGGS. 7 
that is, eggs in which the shell and both membranes are broken, may 
become contaminated directly. 
It has been stated by Kossowicz 1 that the shells of stale eggs offer 
less resistance to bacterial and mold invasion than do those of fresh 
eggs. Even the shells of clean eggs frequently harbor many bac- 
teria and also B. coli. 2 
Experiments have shown that bacteria and molds can penetrate an 
unbroken shell if it is in a moist condition. Water removes the 
mucilaginous coating naturally present on the shells and renders the 
fibrous membrane pervious to organisms. Hen feces and the con- 
tents of broken eggs when damp attach themselves to the shell. 
The dirt then becomes the carrier of the bacteria and the moisture 
presents the mechanical means necessary for their penetration. . 
In the second report 3 of this series, a general survey of the litera- 
ture on bacteria in perfectly fresh eggs was given. Since this bulletin 
was published, Rettger 4 has discussed the results of the bacterio- 
logical examination of 20,000 newly laid eggs. His findings corrob- 
orate those of previous investigators, namely, that, with but few 
exceptions, strictly fresh eggs are sterile; and those which do con- 
tain bacteria have them only in small numbers. These bacteria are 
too few to affect the use of fresh eggs for food, but their presence or 
absence determines the ideal for eggs. The maintenance of low bac- 
terial contents in eggs and egg products, therefore, is one index of the 
efficiency of egg-handling operations. 
Many examples of eggs with high bacterial content are given in 
Department Bulletin 51. It is interesting to note that in those eggs 
in which both the white and yolk were examined, the number of bac- 
teria was markedly greater in the white than in the yolk, a condition 
indicative of bacterial penetration from the exterior. 
EGGS WITH SOUND, CRACKED, AND LEAKING SHELLS. 
As a large percentage of the breaking stock of the cooperating egg- 
breaking plants consisted of eggs with defective shells, a detailed de- 
scription was made of the condition of the shell of each egg in the 29 
experimental samples examined in order to determine the effect of a 
dirty or damaged shell upon the condition of the contents. The re- 
sults of this study are given in Table III and in figure 2. 
The possibility of bacterial penetration increases with the amount 
of damage to the shell. The percentage of eggs containing bacteria 
was as follows: 8.7 per cent of eggs with sound shells, 18.6 per cent of 
eggs with cracked shells, and 30.7 per cent of eggs with leaking shells. 
(Table III, Part I.) The percentage of eggs containing B. coli was 
found also to be dependent upon the condition of the shell (Table III, 
Part III). 
1 Kossowicz, Alexander. DieZersetzungund Haltbarmachung derEier,pp. 42-54. Wiesbaden, 1913. . 
2 Bacteriological Studies on Eggs. Kansas State Agr. Col. Exp. Sta., Bui. 180. 1911. 
s U. S. Dept. Agr. Bui. 51, pp. 3, 4. 1914. 
4 Centbl. Bakt., [etc,} 2 Abt., 39 (1914), 611-624. 
r~~. 
