20 BULLETIN 471, IT. S. DEPARTMENT OF AGRICULTURE. 



molds and bacteria are not injurious to health, while others may 

 give rise to more or less serious illness. The best way to prevent 

 the infection of eggs by molds and bacteria is to produce infertile 

 eggs and to keep them clean and dry from the time they are laid 

 until they are finally used. The coating of mucilaginous material 

 on the outside of the egg and the very thin membrane, or " skin," on 

 the inside protect the egg from the invasion of molds and bacteria. 

 The shell coating is easily removed by water or by rubbing. Also as 

 eggs grow old the natural protection of the egg becomes less effective. 

 Therefore, deterioration due to molds and bacteria is more likely to 

 occur if the egg is washed or the shell becomes moist by being kept in 

 a damp place. If eggs are dirty enoughto wash it is better to do so 

 and use them at once than to " put them down." Neglected and 

 stolen nests (usually dirty and so sources of bacteria, etc.) are prob- 

 ably the chief cause of molded or rotten eggs, and so hens should 

 always have clean, airy nests. Housekeepers who are careful will 

 not choose dirty eggs. If for any reason they must be used they 

 should be carefully washed and wiped. 



These causes of spoiling are important matters for the house- 

 keeper, since they have a bearing on supply and market price. It is 

 to the housekeeper's interest to have only eggs produced under good 

 conditions brought to market, because this means less loss in handling 

 and an increased supply of good eggs, which in turn, affects prices 

 favorably. 



As a means of securing a supply of fresh eggs for table purposes, 

 the purchase of eggs direct from the producer by parcel post is worth 

 consideration by the housekeeper. 



Since eggs vary more or less in size and weight, though very little 

 in composition (see p. 6), it follows that they vary in the amount 

 of food material which they supply. For this reason housekeepers 

 who have a choice very commonly like to select large eggs. That 

 size has an effect on the cost of eggs when they are purchased for a 

 uniform price per dozen is evident when one considers that a dozen 

 pullets' eggs, weighing 18 ounces, at 25 cents per dozen, supplies 

 eggs at 22.9 cents per pound, while hens' eggs, weighing 24 ounces 

 at the same price per pound would supply eggs at 16f cents per 

 pound. Such differences are especially worth considering when eggs 

 are used in quantity. There are few exact household standards for 

 cookery, and using eggs as they come, by number rather than by 

 weight, would probably not imply important variations. However, 

 it is well known that when a recipe calls for 4 eggs one may use 

 instead of 4 of average size either 3 large or 5 small ones. 



For reasons of economy as well as accuracy in cookery there is a 

 growing tendency to use eggs by weight or measure instead of by 



