74 MISSOURI BOTANICAL GARDEN BULLETIN 
came to the same conclusion, reporting that decay was due 
to a series of oxidations and that Appert’s method, by pre- 
venting contact with outside air, stopped the process. Simi- 
lar explanations were made by other scientists, but not until 
the epoch-making investigations of Louis Pasteur was the 
fundamental principle discovered that all decay was due pri- 
marily to the activity of certain microscopic plants—the bac- 
teria. However, the original means devised to exclude the 
air likewise excluded or destroyed the bacteria; consequently, 
the results were satisfactory, regardless of the specific cause 
of the trouble. It may be pointed out, however, that had 
Appert known the real source of the spoiling of foods it 
would not have required fifteen years for him to discover 
the remedy, and that the perfection of the canning industry 
has only been possible through the knowledge obtained from 
the science of bacteriology. 
Successful canning depends, therefore, upon two things: 
first, the killing of all microérganisms within the can or Jar 
of food, and, second, the sealing of the container so that no 
bacteria can enter from the outside. With the exception of 
a few fruits and vegetables which, upon standing, deteriorate 
in flavor and consequently are not worth preserving, the 
spoiling of canned foods is entirely due to the presence of 
bacteria. Either the method of killing the bacteria, com- 
monly called sterilization, is inadequate, or, this being ac- 
complished, bacteria from the outside are permitted to enter 
the can during or after sealing. Carelessness in closing the 
jar or can, whereby bacteria on the hands or a cloth or some 
utensil are communicated to the inside of the lid or jar, may 
result in the loss of the contents, even though the container 
be tightly closed afterwards. Of course, any hole or leak 
around the top of a jar, permitting the entrance of the 
decay-producing organisms, will likewise be disastrous— 
hence the use of the rubber ring on glass jars and of sealing 
wax, etc., for hermetically closing cans. Mere cleanliness, 
as the term is ordinarily used in the kitchen, is not sufficient 
for the preservation of food in containers. Absolute bac- 
teriological cleanliness, the same that is necessary in the lab- 
oratory in the preparation of pure cultures of beneficial or 
disease-producing germs, must be maintained. 
Fortunately, this is a comparatively simple matter, when 
one thoroughly understands the problem involved. While 
commercial canneries, because of the necessity of accom- 
plishing the process on a large scale in a short space of time, 
are provided with elaborate and expensive apparatus, juss 
as satisfactory results may be obtained by any householder 
