Dr. Lucius Nicholls 



239 



of proteids ; other organisms, such as those 

 which putrefy meat, will not flourish upon this, 

 but require the presence of peptone or some 

 other proteid. 



Many media can be prepared upon which 

 the organisms that ferment cacao will flourish. 



I have found the medium with the following 

 composition, the most useful for practical 

 purposes : 



Magnesium sulphate 

 Calcium sulphate 

 Calcium phosphate ... 

 Potassium nitrate ... 

 Sodium chloride 

 Iron perchloride 

 Potato (finely cut up) 



Glucose 



Agar 



Distilled water 



0-5 grm. 



075 

 075 



' O 5 



2 OZ. 



5 

 15 , 

 1,000 c.c. 



This forms a moist, solid medium upon 

 which yeasts, bacteria and moulds flourish 

 luxuriantly. 



It is boiled, filtered, poured off into test 

 tubes, and sterilized in an autoclave ; some of 

 the tubes are sloped (vide fig. 4, p. 240), others 

 are kept for plate cultures. 



I use another medium which contains, starch, 

 alcohol and only a small quantity of sugar, for, 

 the purpose of isolating acetic acid bacilli and 



cocci. 



The method now pursued is to obtain Petri 

 plate cultures from sweating cacao. A plati- 

 num loop is sterilized and pushed into the 



