252 BACTERIOLOGICAL AND ENZYME CHEMISTRY 



may be physically ready to roll before sufficient enzyme is 

 developed ; and on the other hand, in very wet weather, the 

 leaf may be chemically ready for rolUng before it is properly 

 withered. It may be possible, therefore, to control the time 

 of withering, either retarding it by heaping up the leaves or 

 quickening it, e.g., by means of fans, and so obtaining the 

 necessary conditions for the production of the best tea. 



It is of further interest that the amount of enzyme in the 

 leaf has been shown to depend on the percentage of phosphoric 

 acid used in manuring the plants ; 

 further, much more enzyme is present 

 in leaves plucked at 6.30 a.m. than at 

 6 P.M., which supports the suggestion 

 made with regard to the indigo plant 

 in the preceding section. 



The Fermentation of Cocoa. — 



Cocoa, as known to the consumer, is 

 obtained by grinding and roasting the 

 seeds or beans of the cocoa fruit ; the 

 appearance and structure of the latter 

 can be imderstood by reference to Fig. 

 25. In oi'der to obtain the beans free 

 from surrounding pulp, a process of 

 Fig. 25.-COCOA i^tjit fermentation is resorted to. The fresh 

 IN Part Section. beans, after separating them from the 

 shell, are piled on a floor or filled into 

 boxes, and allowed spontaneously to ferment. Plate III (ii) 

 gives an idea of the appearance of these fermenting boxes. 

 A period of two to six days, according to circumstances, is 

 usually allowed for fermentation. A rise of temperature, 

 amounting to about 5° C, takes place in twenty-four hours' 

 and in the course of four days the fermenting beans may have 

 a temperature as much as 18° to 20° C. above the surrounding 

 atmosphere. 



