CLASSIFICATION OF THE ANAEROBIC BACTERIA’ 
HitpA HemMpLt HELLER 
The classification of living forms should depend on an under- 
standing of the laws of heredity as demonstrated in those forms. 
Preliminary classifications are made by applying the machinery of 
arrangement that has been worked out for other groups that are 
well understood, to groups of whose biological processes we know 
little. Preliminary classifications are necessary and are as desirable 
as are catalogues, and should be made to correspond to the known 
life processes of the organisms as nearly as possible, but they should 
only be offered tentatively. 
The study of the biology of the anaerobic bacilli is in its early 
morning twilight. Today the scientific world holds two widely 
opposite opinions in regard to the classification of these organisms. 
The view held in Western Europe and in America is that the 
anaerobic species are many, distinguishable, and not highly vari- 
able; that held by many workers in Central Europe is that the 
species are practically indistinguishable, are highly variable, and 
may be changed one into another. It is impossible to bring these 
two points of view into alignment. They are not to be attributed 
to diverse interpretation of differences that shade into one another. 
They are themselves the outcome of an evolutionary process, 
depending on a mutation in thought, followed by the throwing up 
of a geographical barrier in 1914 that isolated the mutant thought 
and permitted it to overgrow its ancestral types of reasoning in a 
peculiarly favorable soil. The crux of the matter lies in the purity 
of the cultures studied by the classifier. It is notorious that the 
casual worker with anaerobic organisms knows neither how to 
purify them, nor how to tell when they are pure or impure. The 
anaerobes are not difficult to isolate when one knows how, but 
usually workers do not know how. Anaerobes have occasionally 
been isolated in pure culture since the early days of bacteriology. 
* From the George Williams Hooper Foundation for Medical Research, Univer- 
sity of California Medical School, San Francisco 
Botanical Gazette, vol. 73] [70 
