QUALITY IN EGGS 
enough to admit all forms of bacteria, but the membrane 
inside the shell is germ proof as long as it remains dry. When 
this membrane becomes moist so that bacteria may grow in 
it, these germs of decay quickly grow through it and con- 
taminate the contents of the egg. 
Heat favors the growth of bacteria in eggs and sufficient 
cold prevents it, but as bacteria cannot enter without mois- 
ture on the surface of the egg we can consider dampness as 
the cause of rotten eggs. Moisture on the shell may come 
from an external wetting, from the “sweating” of eggs coming 
out of cold storage, or by the prevention of evaporation to 
such an extent that the external moisture of the egg thor- 
oughly soaks the membrane. The latter happens in damp cel- 
pane and when eggs are covered with some impervious ma- 
terial. 
Rotten eggs may be of different kinds, according to the 
species of germ that causes the decomposition. The specific 
kinds of egg rotting bacteria have not been worked out, but 
the following three groups of bacterially infected eggs are 
readily distinguishable in the practical work of egg candling. 
(1) Black rots. It is probable that many different species 
of bacteria cause this form of rotten eggs. The prominent 
feature is the formation of hydrogen sulphid gas, which black- 
ens the contents of the egg, gives the characteristic rotten 
egg smell and sometimes -causes the equally well known 
explosion. 
(2) Sour eggs or white rots. These eggs have a character- 
istic sour smell. The contents become watery, the yolk and 
the whites mix and the whole egg is offensive to both eye 
and nose. 
(3) The spot rot. In this the bacterial growth has not con- 
taminated the whole egg, but has remained near the point of 
entrance. Such eggs are readily picked out with the candle, 
and when broken open show lumpy adhesions on the inside 
of the shell. These lumps are of various colors and appear- 
ances. It is probable that these spots are caused as much by 
mold as by bacteria, but for practical purposes the distinction 
is immaterial. 
In practice it is impossible to separate rotten from heated 
eggs for the reason that in the typical nest of spoiled eggs 
found around the farm, both causes have been at work. Dead 
chicks will not necessarily cause the eggs to decay, but many 
such eggs do become contaminated by bacteria before they 
reach the candler, and hence, as a physician would say, show 
complications. 
The loss of eggs that are actually rotten is not as great 
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