54 



SILOS, ENSILAGE AND SILAGE. 



sugar increases, the latter substance being partly pro- 

 duced at the expense of the former."* M. Cahours,f 

 in 1864, observed that the volume of carbonic acid pro- 

 duced by fruits in ripening, exceeded the volume of 

 oxygen absorbed, so that it was undoubtedly the result 

 of cell metabolism, and not of direct oxidation. 



These observations were confirmed by the experiments 

 of Lechartier and Bellamy, J who also noticed that the 

 development of carbonic acid was not uniformly con- 

 stant, but varied widely at different periods, and that 

 it was more rapid in the day than at night, which is a 

 further indication that it was elaborated as a function of 

 the life of the fruit cells, and that the absorbed oxygen 

 was utilized in these vital activities. But the metabo- 

 lism of the cells in ripening fruits is not limited to the 

 decrease in woody fibre and the exhalation of carbonic 

 acid as the sugar increases. A. Hilger, || in experiments 

 on two varieties of grapes (Austrian and Riesling), found 

 that the acid diminished as the sugar increased, in the 

 process of ripening, as seen in the following table : 



Mercadante found that both malic acid and sugar 

 increased in plums while green, and that tannin dimin- 

 ished, but as the fruit ripened the tannin disappeared, 



* Brown, 1. c. p. 469. 



t Compt. rend. 69, p. 356, as quoted by Lechartier and Bellamy. 



t Compt. rend. 69, p. 466, etc. 



IILandw. vexsuchs-stat. XVII, pp. 245-251. Jour. Chem. Soc., 1875 (28), p. 281. 



