74 



Lectures on Bacteria. 



vm - 



to the endosporous division ; others appear to be arthrosporous, 

 while there is a third group in which the point is not yet ascer- 

 tained, but appearances are in favour of their being kept together, 



as at present, under the same 

 genus. The rod-forms which 

 are not known to be endo- 

 sporous may all be termed 

 Bacterium, and the coccus- 

 forms (page 9) Micrococcus. 

 It is obvious that no sharp 

 line of distinction can be 

 drawn between Micrococci 

 and short rod-shaped Bac- 

 teria, but it is convenient 

 and customary to distinguish 

 them. The species too, which 

 are at present distinguished, 

 require care in their deter- 

 mination. Some of them are 

 certainly known to be fully 

 and clearly distinct ; of others 

 this cannot be said, and 

 their present names in all 

 probability include two or 

 more species which have 

 yet to be studied severally. 

 Thus it seems to me quite 

 certain that more than one distinct species has been described 



Fig. 5. Crenothrix Kiihniana, Rabenhorst. n group of young filaments 

 attached below, a, b older filaments ; at the upper end of b single cells are 

 issuing from the opened sheath, c broad filament with flatly disk-shaped 

 cells in its upper portion, which are divided in basipetal succession along 

 the length of the filament into minute round spore-cells ; the spores are 

 issuing from the uppermost extremity of the open sheath, d, c spores 

 developing into young filaments. After Zopf. n magn. 450, a, b 540, 

 d, e 600 times. 



