2 BULLETIN 51, U. S. DEPARTMENT OF AGRICULTUEE. 
the exact knowledge of the composition or history of the egg itself. 
The farmer's wife, accustomed to the fresh eggs of the farm, dis- 
cards as unfit for food an egg which the city baker would, with a 
clear conscience, serve to his own family. The difference in the point 
of view has progressed even to the savants who have held opposite 
and positive opinions concerning the wholesomeness or desirability 
of certain eggs, especially of those known in commerce as " frozen *' 
or " desiccated." 
Investigation has shown that when the egg is laid it is of a fairly 
constant chemical composition and contains but few bacteria or 
molds. In the vicissitudes of marketing, with its attendant unde- 
sirable conditions, eggs in the shell undergo a variety of changes, 
referable, almost exclusively, to the mode of handling. These 
changes, their effect upon the food and market value of the egg, 
and the means by which they can be reduced to a minimum have 
been, and still are, a subject of investigation by the Department of 
Agriculture cooperatively with every branch of the egg-marketing 
industry. 
The great variety of conditions to which an egg is subjected and 
its sensibility to temperature, humidity, odors, etc., result in many 
evidences of deterioration in the eggs on the market. The extent to 
which such downward changes are reflected in the composition of the 
egg, together with their recognition by physical, chemical, and bacte- 
riologic methods, is the subject of the present report. 
The work has been done as part of an investigation of the prepara- 
tion of frozen and dried eggs. It is the foundation on which to bilild 
all the other phases of the investigation, such as the construction 
of the apartments in which egg breaking for food purposes can pro- 
ceed; the methods used to guard against bacterial contamination; the 
systematic application by the employees in the packing houses of the 
knowledge gained by scientific research to increase accuracy and 
efficiency ; the quality of the output of the houses under old and new 
conditions, and the behavior of those products when they reach the 
hands of the baker, who, for this investigation, may represent the 
consumer. These diverse parts of the work will be reported in a 
series of publications of which this is the first. It will be observed, 
therefore, that the subject is discussed from the industrial viewpoint, 
even though it is essentially a laboratory study. 
The individual eggs, and some of the composite egg samples, were 
opened in the laboratory ; the samples designated " commercial " 
were opened by a bacteriologist in packing houses where the sur- 
roundings were as clean as, or cleaner than, in the laboratory and 
where all utenstils were sterilized. 
The information given in this report has been gathered in south- 
western Iowa, northern Tennessee, and the valley of the Missouri 
from the northern barrier of Iowa to the central part of Kansas. 
