O4 CLASSIFICATION AND DESCRIPTION OF BACTERIA 
reactions for the new strain possessed all of those of the true pneumo- 
coccus. In turn, he was able to change these serum reactions. This 
raises the question with regard to what characters may be depended 
upon for constancy. This work of Rosenow together with the recent 
reports on life cycles may make it necessary to introduce new methods 
of classification. In the study of the higher forms of life the term 
evolution form conveniently lends itself to abnormal shapes. 
Anton van Leewenhoek (1683) was probably one of the first to 
report different kinds of bacteria. From our present knowledge, it is 
doubtless true that he had a mixture of the various forms of micro- 
scopic life. At this time the methods of securing different dilutions 
were not perfected. In fact, no real attempt had been made up to 
this time to secure pure cultures since their necessity for accurate 
bacteriological work had not been realized. Van Leewenhoek recog- 
nized curved and straight forms and presented drawings with his paper. 
This contribution may be considered as a classification only in the 
most general sense and then only to the extent that different shapes 
were observed. It is not certain that he saw many bacteria through his 
crude apparatus. 
Miiller (1786) studied bacteria from a zoological standpoint and 
proposed a classification which never had very extended use. Probably 
he also observed protozoa with perhaps a few bacteria. 
Ehrenberg (1828) began his contributions to systematic bacteri- 
ology by founding the genus bactertum. A résumé of his work is men- 
tioned by Smith. This genus he later divided into several parts. In 
1838 he published his work ‘“ Die Infusionsthierchen’”’ and therein 
describes the genus bacterium as being ‘ Die quergetheilten gehéren 
zu den Zitterheirchen ¢Vibrionen) die langsgehteilten zu den Stabtheir- 
chen (Bacillen).”” Ehrenberg gave us several terms which have been 
retained up to the present time but to which different meanings are 
attached. 
Cohn (1872) published a classification which was used for some time. 
He divided the bacteria into the following four groups: 
I. Sphaerobacteria 
Species 1. Micrococcus, 
II. Microbacteria: 
Species 2. Bacterium. 
III. Desmobacteria: 
Species 3. Bacillus. 
Species 4. Vibrio. 
