CLASSIFICATION OF THE BACTERIA. 51 
Fat globules, which are found of all sizes, are 
often of the same dimensions as Micrococcus, and 
are very difficult to distinguish from the latter. 
The difference in refractive power is slight, and 
the action of re-agents, such as ether, is not cer- | 
tain in mucilaginous solutions. Hiller, who has 
paid especial attention to the means of recognizing 
bacteria, divides them into two groups : — 
A. The optical signs : comprising 1. The charac- 
teristic vegetable form, rods, leptothrix, this he 
recognizes as of little use, as in this case there is 
no doubt; 2. The characteristic movements of the 
monads; 3. The mode of growth and of multipli- 
cation; 4. The mode of junction of the granules. 
B. The chemical signs: 1. False zooglea become 
softened and diffluent under the action of liq. 
potassee, and are coagulated by the direct applica- 
tion of alcohol; 2. In sections of tissues, after an 
hour of maceration in liq. potassee, diluted 5th, 
the monads are colored brown by iodine, while fat 
granules are not. 
But, in truth, the method of cultivation, ex- 
tolled by Cohn and Wollf, is the best means of 
distinguishing the bacteria. ‘The distinction of 
pseudobacteria,” says the first of these authors, 
“from veritable globular bacteria is a problem 
which our microscopists cannot resolve, in every 
case, with the desirable certainty. It is only by 
a study of their mode of development that this 
distinction can be made. The globules which di- 
vide and develop in form of chains are organized 
beings ; when this does not occur, we are dealing 
with pseudobacteria.” 
