THIRD PART. 

 BACTERIA OR SCHIZOMYCETES. 



CHAPTER X. MORPHOLOGY OF THE BACTERIA. 



SECTION CXXIX. The forms which we have now to consider are termed by 

 Nagelt l Schizomycetes or Fission-Fungi ; they are known also by an older 

 name, Bacteria, which was restored by Cohn in 1872 as the designation of the entire 

 group. I prefer the latter appellation for a group which not only includes Fungi in 

 Nageli's sense, namely Thallophytes which have no chlorophyll, but has among its 

 most characteristic members forms which . contain chlorophyll and cannot therefore 

 with any propriety be termed Fungi. I avoid the use of the term Bacterium as a 

 generic name. To denote the species which constitute the genus Bacterium of 

 authors, I use partly the generic name Bacillus which will be more precisely de- 

 fined in the sequel, and partly the name Arthrobacterium, the latter being applied 

 to all species in which endogenous formation of spores, to be described presently, 

 has not yet been observed. It must not be supposed that we have in this way effected 

 a final reform of the nomenclature ; we gain only a short expression for the present 

 state of our still very imperfect knowledge. 



The Bacteria consist of minute cells often less than i fi in. breadth, and are 

 either isodiametric or roundish in shape or else cylindrical and rod-like; they 

 multiply if supplied with a sufficient amount of food by successive bipartitions, each 

 cell dividing into two similar daughter-cells through an unlimited number of genera- 

 tions. The successive divisions are in most cases all in the same direction, and hence 

 all the cells which have proceeded from one initial cell are arranged in a single simple 

 filiform row if they remain united to one another. All the members of the row are 

 alike capable of growth and division. It less frequently happens that, without any 

 other change in the behaviour of the cells, the successive divisions take place in 

 alternately varying directions, so that the arrangement of the generations which 

 continue connected together is from the first other than that of a simple row. 



Verhandl. d. Deutschen Naturforscher-Versammlung zu Bonn. See Bot. Ztg. 1857, p. 760. 



