( 74 ) 



used shaken from the roots of garden-plants, which are no Papilio- 

 naceae, the result is fairly the same ; perhaps the number of the 

 above mentioned oxidising forms is more numerous, but this is still 

 doubtful. 



Otherwise, however, is the result when the soil is examined 

 which adheres to the roots of clover, pease, and beans when these 

 plants are cautiously dug up. When the soil adhering to such roots is 

 rubbed fine and after dilution in water sown on a malate plate we 

 find, after a period of 2 days at 30° C, first that the said oxidising 

 colonies have very abundantly developed. But, besides, among these 

 colonies much larger ones are distributed, which oxidise much more 

 vigorously and prove to belong to Azotobacter, which shows that a 

 distinct relation exists between the distribution of this genus and 

 the said Papilionaceae. Whether this relation will appear to be 

 universal and what may be its signification, further experiments 

 have to decide. 



Chemistry. — "Rapid change in composition of some tropical 

 fruits during their ripening." By H. C. Prinsen Geerligs. 



(Communicated in the meeting of May 30, 1907). 



Some tropical fruits which as a rule are gathered in a green and 

 immature state and allowed to ripen afterwards, accomplish this 

 ripening process so rapidly that within a few days they become 

 tender, well-flavoured and palatable, thus offering a good opportunity 

 for studying the still somewhat mysterious problem of the after- 

 ripening of fruits. 



I. Phenomena during after-ripening, 

 a. Banana (Mus a). 



As a rule the bunches of bananas, which contain fruits in various 

 stages of maturity, are cut from the plant as a whole when all 

 the fruits are still green and are hung up to ripen. At the moment 

 when the bunch is cut none of the bananas are fit for food ; they are 

 hard, tasteless and flavourless, the skin is thick, contains much latex 

 and tannin and adheres to the fleshy part. After a few days the 

 skin becomes thin and yellow and can easily be detached, whilst 

 the edible matter is now tender, sweet and well-flavoured. A couple 

 of days afterwards the fruit is unpalatable again owing to overripeness 

 and decay which change it into a soft mass. 



