I04 Journal of Agricultural Research voI.v.no.s 



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 atmo'spheres 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 



