226 The Fermentation of Cacao 
beans by the agency of flies. In the present 
system employed | 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 larvze 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 
ina 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, 2 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 
