56 MORPHOLOGY OF THE BACTERIA. 



one studies the inferior species. The only char- 

 acter which appears general is the presence of 

 chlorophyll in the algae and its absence in the 

 fungi. But, if we adopt this distinctive character, 

 and apply it in all its rigor, we are obliged to 

 separate in the inferior algae some forms very 

 nearly related, and which do not differ from their 

 relations except in this particular. And this is ex- 

 actly what happens in the case of the bacteria. 



In truth, the bacteria, although entirely with- 

 out chlorophyll, have numerous affinities as to 

 form, movement, etc., with the oscillatoriacece, 

 and, according as one or the other of these char- 

 acters have appeared to predominate, the bacteria 

 have been classed as algae or as fungi. 



It is thus that Davaine, Rabenhorst, then Cohn, 

 struck above all by the resemblance of form, mode 

 of grouping, and of multiplication, have placed 

 the bacteria among the algae. Cohn insists, above 

 all, upon the affinities of the filiform bacteria with 

 the beggiatoa and the leptothrix ; of the micrococ- 

 cus, and of the bacterium, with the chroococcacece. 

 He at first placed them at the commencement of 

 this last series ; but we shall see further on that 

 in his last publications he has disseminated them 

 among the oscillatoriaceae and the chroococcaceae. 



Robin and Nageli, on the other hand, insist 

 rather upon the affinities of the bacteria with the 

 yeast plants, which are incontestably fungi, and 

 they include them in this class. 



Robin says expressly : " All the corpuscles de- 

 scribed under the name of Bacterium termo, B. 



