104 
Journal of Agricultural Research 
Vol. V, No. 3 
of infection with any germs of disease or decay, the fruit loses water and 
shrivels up to a withered mass. The group of changes that take place 
during the second of these stages—i. e., the period between the cessation 
of growth and the disintegration of the tissue until it becomes soft or 
mushy—will be termed the “ripening process.'’ 
The object of all storage or preservation of fresh fruit is to slow up 
the ripening process and so to prolong this period as much as possible. It 
is a well-known fact that temperature has an important effect upon the 
rapidity with which these changes take place. It was the object of the 
studies referred to above to determine whether other factors also influence 
the rate of these changes and whether they are due in part to infection 
with disease germs or are wholly enzymic in character. 
Two general methods of study were attempted. First, an attempt 
was made to surround individual apples with a film or coating which 
would prevent gaseous exchanges and bacterial infection. Repeated 
efforts to secure a perfect film of this sort with a variety of different 
materials proved failures; so this method was abandoned. The second 
method involved the sealing up of the apples in atmospheres of different 
pure gases under as nearly sterile conditions as possible in order to pre¬ 
vent both disease infection and the ordinary gaseous exchanges. Sev¬ 
eral large glass bottles, each capable of holding about a peck of apples, 
were fitted with tight stoppers provided with a glass inlet tube reaching 
to the bottom of the bottle and an exit tube extending just through the 
cork. Carefully washed apples were rinsed in a dilute solution of for¬ 
maldehyde, followed by distilled water, and immediately introduced 
into the jars and the stoppers sealed in. The apples were of the Alex¬ 
ander variety and were almost ripe—i. e., they would only keep a few 
days longer without becoming soft. After sealing in the stopper the 
inlet tube was connected to a supply of pure gas and the latter passed 
through until no air could be detected in the gas issuing from the exit 
tube, when the glass tubes were melted off, thus effectively sealing the jars- 
This method did not, of course, remove the air contained in the tissues 
of the apples themselves, but this was relatively small in amount. 
Each of five jars was filled with one of the following gases: Hydrogen, 
nitrogen, oxygen, carbon dioxid, and sulphur dioxid; a sixth was sealed 
with its ordinary air content. No moisture-absorbing material was 
placed in the jars, as it was thought that this would produce abnormally 
rapid losses by evaporation from the tissues of the fruit. Further, the 
recognized chemical changes in the fruit during the ripening process are 
probably not influenced by the moisture content of the surrounding air, 
so that the saturation of the air in the jars with water vapor evaporated 
from the fruit would not be likely to influence the nature of these changes, 
while constant absorption of this vapor would mean rapid shriveling of 
the fruit. 
The jars were left in a warm, light laboratory and were examined 
from time to time. The apples in air continued to ripen normally and 
