1912.] On the Systematic Position of the Spirochcets. 191 



axial thickening of the pellicle which I believe to be homologous with the 

 crista of Cristispira and the axial fibre of Spirochceta. 



In fine, I believe that I have been able to show that, with one exception, 

 all the chief characters of the Spirochaets are to be found represented in the 

 Bacteria. Beyond a doubt, the Spirochaetoidea resemble both the bacillar and 

 and spirillar forms of bacteria very closely. There is but one peculiar 

 character which the Spirochaets possess — namely, the power of active 

 movement without the aid of flagella or other organs of locomotion. No 

 known bacteria, so far as I am aware, possess such a power. 



As I believe I have been able to establish all the foregoing points in the 

 morphology of the Spirochaets and the Bacteria, I think I am justified in drawing 

 the conclusion that the two groups of organisms cannot be separated systemati- 

 cally. In other words, the Spirochaets must be classified with the Bacteria. 



The group of the Haplobacteria, as at present constituted, contains three 

 different sets of forms — bacillar, spirillar, and coccus forms of bacteria. The 

 distinction between these is, in all probability, in many cases purely arbitrary, 

 owing to the fact that many of the Bacteria are pleomorphic. For systematic 

 purposes, however, it is convenient to subdivide the Haplobacteria into these 

 three groups, which I may call Bacilloidea, Spirilloidea, and Coccoidea. I 

 believe that the Spirochsetoidea should, for the present, be regarded as a 

 group of the same systematic status — whatever that may be. I fully realise 

 that the classification of the Bacteria is, at present, impossible. It will be 

 possible only when the morphology and life-histories of these organisms are 

 more fully known. 



It is possible that many Spirochaets are transient forms of pleomorphic 

 organisms. I would suggest that the " granules " and " spores " described by 

 several workers in several different Spirochaets are really coccus forms of 

 these bacteria. 



The systematic position which I would assign to the Spirochaets is shown 

 in the following scheme : — 



r Cyanophyceaj 



SCHIZOPHYTaJ rT-^T, 4- ■ f Goccoidea 



r I ncho bacteria 

 (.Bacteria -j | Bacilloidea 



[ Haplobacteria <j 



j Spirilloidea 



L Spirochsetoidea -{ 



j Cristispira. 



^ Saprospira. 



A full account of my researches — with illustrations, a detailed analysis, and 

 references to the literature — will appear later. 



