MONERA 



colorless bacteria are without the important green, 

 blue, or red coloring matter (phycocyan) which tints 

 the plastids of the chromacea, and is the real instrument 

 of the carbon-assimilation. However, there are excep- 

 tions in this respect: bacillus virens is tinted green with 

 chlorophyll, micrococcus prodigiosus is blood-red, other 

 bacteria purple, and so on. Certain earth-dwelling 

 bacteria {nitrobacteria) have the vegetal property of 

 plasmodomism ; they convert ammonia by oxydation 

 into nitrous acid, and this into nitric acid, using as their 

 source of carbon the carbonic acid gas in the atmosphere. 

 They are thus quite independent of organic substances, 

 and feed, like the chromacea, on simple inorganic com- 

 pounds. 



Hence the ai^nity between the plasmodomous chro- 

 macea and plasmophagous bacteria is so close that it is 

 impossible to give a single safe criterion that will effect- 

 ually separate the two classes. Many botanists accord- 

 ingly combine both groups in a single class with the 

 name of schizophyta, and within this distinguish as 

 "orders" the blue-green chromacea as schizophyccce 

 (cleavage - algae) and the colorless bacteria as scJiizo- 

 mycetes (cleavage-fungi). However, we must not take 

 this division too rigidly; and the absolute lack of a nu- 

 cleus and tissue-formation separates the chromacea just 

 as widely from the multicellular tissue-forming algae as 

 the bacteria from the fungi. The simple multiplication 

 by the halving of the cell, which is expressed in the name 

 "cleavage-plants" {schizophyta), is also found in many 

 other protists. 



The number of forms that can be distinguished as 

 species in the technical sense is very great in the case of 

 the bacteria, in spite of the extreme simplicity of their 

 outward appearance; many biologists speak of several 

 hundred, and even of more than a thousand, species. 

 But when we look solely to the outer form of the living 



20I 



