CLASSIFICATION. 11 



Having determined that the bacteria are truly vegetable organ- 

 isms, the attention of botanists has been given to the question as to 

 what class of vegetable organisms they are most nearly related to. 

 There are decided differences of opinion in this regard. While Da- 

 vaine, Rabenhorst, and Cohn insist upon their affinities with the 

 alga3, Robin, Nageli, and others consider them fungi. One of the 

 principal characters which distinguish the alga3 from the fungi is 

 the presence of chlorophyll in the former and its absence in the latter. 

 Now, the bacteria are destitute of chlorophyll, and in this regard 

 resemble the fungi; yet in others their affinities with the Palmellacece 

 and Oscillatoriacece are unmistakable. It is not necessary, how- 

 ever, that we should consider them as belonging to either of these 

 classes of the vegetable kingdom. By considering them a distinct 

 class of unicellular vegetable organisms, under the general name of 

 bacteria, we may avoid the difficulties into which the botanists have 

 fallen. 



We must refer briefly, however, to the classification, proposed by some 

 of the leading- German botanists. 



Nageli, placing 1 the bacteria among 1 the lower fungi, which give rise to 

 the decomposition of organic substances, divides these into three groups: 



1. The Mucorini, or mould fungi. 



2. The Saccharomycetes, or budding fungi, which produce alcoholic fer- 

 mentation in saccharine liquids. 



3. The Schizomycetes, or fission fungi, which produce putrefactive pro- 

 cesses, etc. 



Cohn, under the iiamo of Schizophytes, has grouped these low vegetable 

 organisms, whether provided or not with chlorophyll, into two tribes hav- 

 ing the following characters: 



1. GLJEOGENES cells free or united into glairy families by an intercel- 

 lular substance. 



2. NEMA.TOGEXES cells disposed in filaments. 



In the first tribe he has placed the genera Micrococcus (Hallier), Bacte- 

 rium (Dujardin), Merismopedia (Meyer), Sarcina (Goodsir),and Ascococcus 

 (Billroth), with various genera of unicellular algae containing chlorophyll. 



In the second tribe we have the genera Bacillus (Cohn), Leptothrix 

 (Kg.), Vibrio (Ehr.), Spirillum (Ehr.), Spirochcete (Ehr.), Streptococcus 

 (Billr.), Cladothrix (Cohn), and Streptothrix (Cohn), associated with gen- 

 era of green filamentous algae. 



The German botanist Sachs unites the fungi and the algae into a single 

 group, the Thallophytes, in which he establishes two parallel series, one in- 

 cluding those containing chlorophyll, and the other without, as follows: 



THALLOPHYTES. 



Forms with chlorophyll. Forms without chlorophyll. 



Class I. Protophytes. 



A. Cyanophyceae (Oscillatoria- A. Schizomycetes (Bacteria), 

 ceae, etc.). 



B. Palmellaceae. B. Saccharomycetes. 



