62 MORPHOLOGY OF THE BACTERIA. 



all true, he says, of the spirilla, which are not only 

 distinguished from the rod bacteria, properly so 

 called ; but which present in their species some 

 differences as constant as any well-defined species 

 of alga or of infusoria. 



Hallier, Hoffmann, Billroth, Robin, Nageli, etc., 

 consider the different forms of bacteria in a very 

 different fashion. According to them they are 

 not autonomous species, but phases of development 

 of one or of several species. 



According to Hallier, we may see, a propos of 

 the polymorphism of the bacteria, the singular 

 transformations which he has obtained by their 

 cultivation. 



-According to Billroth, the bacteria belong to a 

 single species of plants, the Coccobacteria septica, 

 with the exception of the Spirillum and Spirochceta, 

 in regard to which Billroth is not willing to give 

 an opinion. This view has been adopted by a 

 certain number of microscopists, and above all by 

 the pathologists, such as Frisch, Tiegel, etc. 



Robin also admits the genetic relation of Micro- 

 coccuSj Vibrio, Bacterium and Leptothrix, but con- 

 siders them the distinct and successive phases in 

 the evolution of several species : 1st. Corpuscles 

 described under the name of Bacterium termo, 

 punctum, etc., Micrococcus ; 2d. Mycelial fila- 

 ments, Vibrio, etc. ; 3, Bacteria, Bacteridies, Micro- 

 bacteria, etc. ; 4th. Leptothrix and forms more 

 advanced. 



The opinion of Nageli corresponds very nearly 

 with the preceding. " As much as I am con- 



