238 MASS. EXPERIMENT STATION BULLETIN 180. 



Effect of Different relative Humidities on Spoilage due to 

 Carbon Dioxide. 



Most of the tests described above had been made in atmospheres having 

 relatively high moisture content. In order to determine whether the hu- 

 midity of the air in any way influenced the spoUage, a series of tests was 

 run in which sound cranberries of the Howes variety weie kept in tightly 

 sealed Hempel desiccators which were maintained at constant humidity 

 by sulfuric acid solutions of different densities. This method has been 

 described by one of the writers in an earlier paper. "• All these tests were 

 made at a temperature of about 24° C. 



Chambers having relative humidities of 100 per cent, (saturated atmos- 

 phere), 75 per cent., 50 per cent., 25 per cent, and approximately per 

 cent, were used, and so far as could be detected by careful observation 

 there was no difference in the rate of spoilage at the different humidities. 



Relation of Fungi to Spoilage dub to Carbon Dioxide. 



It is of course possible that one effect of accumulation of carbon diox ) 

 at least in small amounts, may be to make the berries more susceptible to 

 the attacks of fungi. It seems certain, however, that the injury to the fruit 

 is in many cases wholly independent of the action of fungi. 



On March 13, 1917, we received from Dr. FrankUn a box of Pride cran- 

 berries taken from a crate of fruit which had been kept in storage in the 

 basement of the screenhouse at the State experimental bog at East Ware- 

 ham. These were taken to represent the average condition of the spoiled 

 fruit at the time. This lot contained 271 berries. They were carefully 

 sorted, and 195 were somewhat softened and flaccid, having much less resil- 

 iency than the rotten fruit, in which the tissues are more or less destroyed 

 by the growth of fungi. They had the same general appearance as berries 

 treated with carbon dioxide, and their condition was believed to be due 

 to the time and manner in which they had been kept rather than to fungous 

 disease. Fifty of these berries were taken at random and cultures made by 

 transplanting the bulk of the pulp from the cranberries, the skin being re- 

 moved. Of these cultures, but 2, or 4 per cent., produced fungi. Assum- 

 ing that this represents the average number afl'ected with fungous disease, 

 deducting 4 per cent, from the total, 195, would leave 187 presumably 

 free from fungous disease. Cultures were also made from the tissue of the 

 remaining 76, which had more the appearance and character of fruit at- 

 tacked by fungi. The results of these cultures showed, however, that 49 

 of these berries were apparently destroyed by some other cause than fun- 

 gous disease, thus maldng a total of 236 out of 271, or 87 per cent., not 

 destroyed by fungi but presumably by the period and conditions of 

 storage since picking. 



» Stevens, Neil E.: A Method for studying the Humidity Relations of Fungi in Culture. 

 Phytopathology, 6, 428-432, 1916. 



