226 The Fermentation of Cacao 



beans by the agency of flies. In the present 

 system employed I believe this last is of the 

 greatest importance ; it is not, however, with- 

 out its disadvantages, as will be shown later. 

 In many places this carriage of yeasts to cacao 

 by flies is the most unvarying factor. 



In order that a rapid and effective fermenta- 

 tion may take place, it is necessary that a fair 

 number of organisms are early and evenly 

 introduced ; for this the condition of the 

 atmosphere is far too variable, because the 

 number of air-borne organisms depend upon 

 the wind, the degree of humidity, and the 

 amount of rainfall. 



Around cacao boxes in the West Indies 

 will always be seen innumerable small flies, 

 and if the sweating cacao is carefully examined 

 numbers of small maggots, the larvae of these 

 flies, will be found. So rapidly does this fly 

 develop that the third day after the deposit 

 of the eggs the maggots crawl to some dry 

 surface on the boxes or their lids, and there 

 their integuments harden into a puparium, and 

 in a few days the flies emerge ; a week is the 

 average length of time occupied by the entire 

 development from egg to fly. 



This little fly is depicted in fig. 2. It is 

 named Drosophila melanogaster. Fig. 2, A, re- 

 presents the fly greatly enlarged, B represent- 

 ing the actual size, about a twelfth of an inch 

 in length. The males can be distinguished 

 from the females by the lower segments of 



