Dr. Lucius Nicholls 241 



and in twelve hours small white colonies will 

 be seen appearing. What has happened is 

 that in the dilutions the organisms were 

 widely separated, and thus, when mixed with 

 or passed over the solid media, they fell in 

 different places and thus each organism grew 

 into an isolated colony. 



These colonies are each touched with the 

 point of a platinum needle, and the point 

 smeared upon the sloped surface of medium in 

 a test-tube (vide fig. 4) ; this is incubated, and 

 the next day a luxuriant growth of a separated 

 organism is present in the tube. Thus there 

 has been isolated an organism in pure culture. 

 Now its action can be tested upon various 

 substances, such as suo-ar or the saccharine 



o 



pulp of cacao. 



By these methods the organisms which are 

 present in the sweating-boxes on the different 

 days can be isolated and their actions tested. 

 By the number of colonies of yeasts and other 

 bacteria, the proportions of these to one 

 another can be gauged on the different 

 days. 



At the same time that cultures are taken 

 from the sweating-boxes, smears are made on 



o 



microscopical slides from the adherent pulp ; 

 these are stained with carbol thionine blue, 

 or some other aniline dye, also by Gram's 

 method, and examined under the microscope, 

 using magnification power of 1,000. 



By the nature of the organisms present the 



16 



