While we have called attention to evaporation as the most pronounced fault of fall eggs, losses from other causes are greatly increased by the holding process.

If the eggs are held in a warm place, heat and shrinkage will case the greatest damage; if held in a cellar, rot, mold, and bad odors will cause the chief loss.

The loss due to shrunken eggs is not understood nor appreciated by those outside the trade.  Such ignorance is due to the fact that the shrunken is not so repulsive as the rotten or heated egg.  But the inferiority of the shrunken egg is so well appreciated by the consumer that high class dealers find it impossible to use them without ruining their trade.  The result is that shrunken eggs are constantly being sent into the cheaper channels, with the result that all lower grades of eggs are more depreciated in the fall of the year than at any other time.

In the classes of spoiled eggs, of which we have thus far spoken, the proverbial rotten egg has not been considered.  The term “rot” in the egg trade is used to apply to any egg absolutely unfit for food purposes.  But I prefer to confine the term “rotten egg” to the egg which contains a growth of bacteria.

The normal egg when laid is germ free.  But the egg shell is not germ proof.  The pores in the egg shell proper are large 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 contaminate the contents of the egg.

Heat favors the growth of bacteria in eggs and sufficient cold prevents it, but as bacteria cannot enter without moisture 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 thoroughly soaks the membrane.  The latter happens in damp cellars, and when eggs are covered with some impervious material.

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 sulphide gas, which blackens 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 characteristic sour smell.  The contents become watery, the yolk and the whites mix and the whole egg is offensive to both eye and nose.