Marks , employed for classifying the Schizomycetes. 1 2 1 
culties of this type are by no means overcome. Hueppe, 
among his numerous other contributions to bacteriology, has 
shown clearly how much the formation of zoogloea depends 
on circumstances, and is therefore a character to be employed 
very cautiously in distinguishing genera and species. 
Zopf, in 1885, devised a scheme of classification which, in 
spite of the admitted difficulties in practical application, has 
the merit of being a very praiseworthy attempt at a scientific 
summary of our knowledge. It differs from the preceding 
especially in that the author tries to bring out the poly- 
morphy of the Schizomycetes. Zopf divides these organisms 
into four main groups, as shown in Table VI. 
TABLE Ml.— Zopf 1885. 
I. COCCACEAE. 
Only cocci or serial chains or groups of cocci, so far as is known. 
No spores known. Divisions in i, 2, or 3 planes. 
A. Divisions in one plane only ; the cocci in moniliform series, 
but separating later. 
Streptococcus. 
B. Divisions in two planes at right angles, leading to the forma- 
tion of plates ; the cells separating eventually. 
Merismopedia. 
C. Divisions in three planes, and therefore leading to the forma- 
tion of packet-like colonies ; the cells separating later. 
Sarcina. 
D. Divisions in one plane only, and the cocci separate at once, 
forming irregular or botryoid groups. 
Micrococcus (with Staphylococcus). 
E. Like Micrococcus , but the colonies immersed in dense 
gelatinous investment. 
Ascococcus. 
II. Bacteriaceae. 
Usually presenting coccus — (may be absent), — rodlet, — and filament- 
ous forms ; the rodlets and filaments being spirally curved or straight, 
and presenting no difference between base and apex. Divisions in one 
plane only, so far as known. Spore-formation known in some : in 
others unknown and perhaps absent. 
