WHAT Are bacteria. 47 



Van Tieghem and De Bary, followed by Hueppe, laying 

 great stress on the method of reproduction, have made two 

 great divisions of bacteria — those which form endospores and 

 those which form arthrospores ; but as Fliigge points out, 

 this division is of little service for practical purposes, as 

 spore formation is at present so imperfectly understood, that 

 it is most difficult to follow the exact method of sporogenous 

 reproduction in a Schizophyte. Winter and Fliigge attempt 

 to get rid of their objection to Cohn's classification by speci- 

 ally modifying it to contain only the pathogenic organisms. 

 They take no account, as already stated, of any morphological 

 developmental cycle or of any biological features, but they 

 give a useful and practical classification. 



Quite recently it has been suggested that bacteria should 

 be classified according to the number and arrangement of 

 the flagella developed, but as such classification is necessarily 

 based on a single characteristic, and that one of the least 

 important, and. as it will be some time before a complete 

 examination can be made in order to determine the number 

 and arrangement of these flagella, such a classification may 

 for the present be left out of consideration. The same 

 holds good as regards Baumgarten's classification ; he 

 divides bacteria into two groups — those which appear to 

 assume a single form only (the Monomorphic) and those in 

 which pleomorphism is a well-developed characteristic. In 

 each he has three genera. In the first : the coccus, the 

 bacillus and the spirillum ; and in the second : the spirulina, 

 the leptothrix and the cladothrix. A similar remark applies 

 to these, however, that applies to Zopf's classification. It 

 may be of some service as a provisional classification, 

 especially to those who are engaged in the study of the 

 morphology and life history of bacteria. To the pathologist, 

 however, these classifications are of comparatively little value 

 except in so far as by their aid the morphologist is able to 

 supply him with information as to the life history of bacteria 

 outside the body. 



Literature. 



Author already quoted. Hueppe. 

 BucHNER. — Centralbl. f. Bakt. u. Parasiteuk. Bd. iv., 1888. 

 CoHN.— Beitr. z. Biol. d. Pflanzen. Bd. i.. Heft. 2, 1872 ; 

 Bd. I., Heft. 3, 1875. 



