50 MORPHOLOGY OF THE BACTERIA. 
they exhibit the brownien movement, are easily 
enough distinguished from Micrococci by optical 
signs, their angular form, their less refractive 
power, and finally by their reaction with certain 
chemical agents; above all if they are mineral 
substances, crystalline bodies, ete. 
It will not be the same with molecular granules 
of organic nature. They have as common charac- 
ters, their rounded form, their notable refractive 
power, movements. Nevertheless, their form is 
less regular, more angular, their color variable, their 
refractive power always less. In doubtful cases, 
Tiegel has given a method which enables us to dis- 
tinguish them from Micrococci. It consists in 
warming the glass slide which supports the cor- 
puscles under examination, if they are “ Coccos,” 
they are seen to move in a manifest manner. 
This does not occur in the case of molecular gran- 
ules. 
It is these productions which render it very 
difficult to observe the phenomena which occur 
during the coagulation of milk. The caseine sep- 
arates in the form of extremely minute globules 
having a very rapid molecular movement. But 
we may distinguish these from bacteria by the 
use of liquor potassz, which dissolves the former 
without attacking the latter. 
As another example of pseudobacteria, 1 will 
mention, after Cohn, the form which fibrine as- 
sumes when it separates from the plasma of the 
blood. It disposes itself in very slender filaments, 
closely resembling filamentous bacteria. 
