BACTERIA IN EGGS 267 
which heat will pass to the middle of the can was not recognized 
until many losses had resulted from insufficient heating But 
the failures proved instructive, and after bacteriologists studied 
the different problems presented by the attempts to can food 
stuffs, the questions were answered one by one, and successful 
rules were devised for the canning of any food products subject 
tosuch methods. To-day failures are rare and are all attributable 
to carelessness in the process. So thoroughly has this subject 
been mastered that to-day any food that can stand heat may be 
perfectly preserved by boiling and canning. Of course the 
flavors are commonly changed by the process, and few of them 
appear like the fresh material. But usually the flavors are less 
changed than by any other method of preservation, and canned 
goods are vastly superior to the dried foods with which our grand- 
fathers were forced to be content in winter Canning is especially 
adapted to foods containing a good deal of water, and hence is 
of especial use among foods that cannot be well preserved by 
drying Fruits are well adapted to canning, but ill adapted to 
drying, and are ruined by salting. 
BACTERIA IN EGGS 
The presence of bacteria in eggs results in trouble experienced 
by every farmer, and one which it seems impossible to avoid. 
It might be supposed that eggs, when freshly laid, would be free 
from bacteria and hence not liable to decay. But this is certainly 
not the case. Bacteria are known to enter the oviduct and 
contaminate the mass of the egg even before its shell is deposited. 
Hence when the egg is laid it will commonly contain bacteria 
in greater or less numbers. These bacteria can obtain plenty 
of oxygen from the air that enters through the porous shell, and 
are thus able to grow readily within the egg, where they soon 
cause its decay. A bacteriological study of eggs has shown quite 
a number of different bacteria in perfectly whole eggs, freshly 
laid, and there seems to be no possible means of avoiding them 
