STORAGE, RESPIRATION, AND GROWTH. 11 



that the acid flavor of green fruits was produced by oxygen, which 

 was only very feebly held in combination in the fruit. 



This first paper by Couverchel gives results of the analysis of juice 

 of apricots and grapes at different stages of growth, determinations of 

 density, acidity, dry weight (in vacuo), gum, sugars (weighed as dried 

 sirup), ash, and soluble ash. 



In the second contribution, in 1831, a further quotations from early 

 writings are given. Of much interest is that from the work of 

 Ingenhouz : b 



All fruits, day and night, exhale a mephitic air, and possess the power to render 

 the surrounding air unwholesome. I have been very much astonished to find a 

 poison in fruits which are so much eaten, the more since the finest fruits possess 

 this power in high degree. * * * 



Couverchel differed from his predecessors, believing the presence 

 of air to be only incidental in the ripening of fruits, and that ripening 

 goes on by action of principles contained in the fruit. It may be, he 

 says, that the sap becomes acidified in its passage through the young 

 branches to the ovary by reason of the decomposition of water and 

 absorption of the oxygen. The acids so formed may act on the gela- 

 tin and give rise to sugars, sugars being considered as intermediate 

 substances between the mucilages and the vegetable acids, containing 

 more oxygen than the former and less than the latter. 



In 1844 Fremy c discussed the work of Berard on the respiration of 

 fruits. He confirmed the observation that fruits consume oxygen, 

 giving off carbon dioxid, and carried out an experiment similar to 

 those of Berard. In Fremy's work the unripe fruit, attached to the 

 tree instead of being kept in a closed jar as in the experiments of 

 Berard, was coated with varnish, in this way stopping the normal 

 respiratory changes. Growth was found to cease, as in the experi- 

 ments of Berard. 



The air contained in green and in ripe fruits was analyzed by boiling 

 slices of the fruit in brine and analyzing the air which separated. 

 The presence 'of a ferment causing the respiratory changes was sug- 

 gested, although a pear, after it was ground, gave off no carbon dioxid 

 gas, whereas before grinding carbon dioxid was freely evolved. 



The old idea that the acids change in ripening (see p. 10) was refuted 

 in the case of grapes, by the recognition of tartaric acid in the very 

 young fruit. 



Unripe fruit was profoundly altered by soaking in dilute sodium 

 carbonate, but no conclusions are drawn. Objection is made to the 

 statement that starch can form the sugar found in fruit, since the sugar 



Loc. cit. 



&Versuche mit Pflanzen, 1786, 1: 64; 2: 61, 221, through Gerber, loc. cit. 



cCompt. rend., 1844, 19: 784. 



