Dr, Lucius Nicholls 241 
and in tweive 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 (vede 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 sugar or the saccharine 
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 
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 
