( 81 ) 



Unlike the after-ripening of the former three fruits, this one is not 

 due to saccharification of starch. The amount of sugar before and 

 after the full ripening is the same hut in this case the fruit has 

 become palatable by the softening of' tho hard pectin and by I lie 

 deposit of tannin and gutta-percha from the juice as insoluble bodies. 



I have to mention here that I did not find lactose in this fruit 

 which has been stated by Bouchardat as being one of its constituents. 

 They, however, contain much pectin and owing to the presence 

 of this body the juice yielded a fair amount of mucic acid on oxidation 

 with nitric acid; this renders the supposition probable that this acid, 

 considered by Bouchardat as an evidence of the presence of lactose, 

 has simply come from the pectin. 



77. Agents of the saccharification during after-ripening. 



When studying the fruits which come first into account in the 

 research under consideration, viz. the banana and the mango fruit, 

 we found in a certain stage of the development a rather sudden 

 transformation of starch into sucrose, followed in a later stage by 

 inversion and partial transpiration of the products of inversion. From 

 experiments on the determination of the carbonic acid in the atmosphere 

 in which this sudden transformation took place, I came to the con- 

 clusion that just the period of the rapid saccharitication coincided 

 with a strong development of carbonic acid, or with a powerful 

 oxidation and degradation. At the same time the moisture on the 

 inside of the glass bell jar in which the fruits ripened showed that 

 a copious evaporation had accompanied the oxidation. 



The figures for the carbonic acid from the bananas showed on 

 the second day a strong development which decreased very soon, 

 whilst those for the mangos remained somewhat stationary for 

 the three days under observation. These data correspond very well 

 with the more rapid after-ripening of the former fruits during this 

 experiment in which they turned from green into yellow even on 

 the second day. 



The transformation is therefore accompanied by oxidation and 

 I tried to check it by excluding the fruits from the free access 

 of oxygen. To this end I covered a few green mango and banana 

 fruits with collodion and kept them together with a few similar 

 fruits not covered with an impermeable layer. The fruits covered 

 with collodion did not ripen well, and were converted into decayed 

 masses, while locally the wrinkles occasioned by the dying off of the 

 fruit caused the collodion layer to burst and thus made the experi- 



6 



Proceedings Royal Acad. Amsterdam. Vol. XI. 



