2Q THE FLORA OF NEBRASKA. 



Bacteria increase by the simultaneous breaking up of the cell into numerous 

 parts, or by the repeated division of the cell. The resulting cells either 

 remain more or less loosely aggregated into a colony (Micrococcus), or 

 agglutinated into a thread (Leuconostoc), or they develop flagella and 

 swim away as free individuals (Bacterium, Spirillum). In addition to 

 division in one direction, it may result in two directions (Lampropedia), 

 or in three directions (Sarcina). The pseudo-branching in forms of 

 Cladothrix is but an irregular modification of division in a single plane. 

 Spores, which subserve the same purpose as the resting spores of higher 

 forms, are of two sorts— endospores and arthrospores. The former 

 arise within the cell either by the condensation of part of the cell-plasm 

 or by the rounding up of the entire contents of the cell. The arthro- 

 spores are produced by the metamorphosis of the whole cell. 



The relationship of the Bacteriacsae to the Schizophyceae is so very close 

 that it becomes necessary to regard them as a highly specialized branch 

 of that class, summing up in their diverse forms the ultimate develop- 

 ment by degradation of the types of the various families of the Schi- 

 zophyceae. No distinct or valid line can be drawn between the lower 

 algae and the bacteria. Undoubted algae, such as Oscillaria and Phor- 

 midium, pass gradually through such intermediate forms as Beggiatoa, 

 Rasmussenia, and Spirillum, into indubitable bacteria, Bacillus, Clostri- 

 dium, and Bacterium. Recent works on zoology have taken the Bacter. 

 iaceae into the animal kingdom, connecting them with the Flagellata 

 through the Monads. Whatever similarity exists between the two groups 

 is, however, much more probably due to convergence or parallelism in 

 development than to any true genetic connection. 



SYNOPSIS. 



Coccobacteria.— Cells globose or ellipsoid, non-motile. 



Micrococcus.— Individuals free or irregularly grouped. 



Streptococcus. — Individuals concatenate. 



Lampropedia.— Individuals in regular colonies. 

 Eubacteria — Cells oblong, bacillar, or filamentous, generally motilo. 



Bacterium.— Cells short-oblong, spores unknown. 



Bacillus.— Cells bacillar, spores endogenous. 



Spirillum.— Cells elongate, spirally twisted. 



Rasmussenia.— Cells filamentous. 



1. MICROCOCCUS Cohn Beitr. Biol. Pflan. I. 2, 151. 1875. 



Cells globose or ovoid, single or aggregated into irregular masses (zoogloea), 



non-motile; spore-formation unknown. 

 Etymology: Greek uxpog, small, and kokkoq, berry. 



Micrococcus amylovorns Burkill in Meth. Oest. Vers. Stat. f. Br. n. M. I. 



1888, p. 30. 



Cocci 1-1.2 fi long, scarcely as wide, generally single, exceptionally aggregated, 



never catenate. 

 In leaves of Pirus malus, causing blight. 



2. STREPTOCOCCUS Billr. em. Zopf Spaltpilz. 51. 1883. 



Cells globose or short ellipsoid, remaining attached after division, spore for- 

 mation unknown. 

 Etymology: Greek crpEnrog, bent, and kokkoq, berry. 



