Il8 TAXONOMY 



in a great many of the lower bacteria resembles, as much if 

 not more, the chitin of certain animal cell walls than it does 

 the cellulose of plants. 



2. The form or shape of the bacterial cell is very similar to 

 some of the low plants, such as the blue-green algae. The 

 bacteria in some cases form filaments, as plants of a low 

 order do. 



3. There is a similarity between certain of the low plant 

 forms, such as the fungi and the bacteria, in their physio- 

 logical processes, as, for example, the assimilation of nutritive 

 products and reproduction. They also resemble certain of 

 the protozoa in the latter process. 



4. The food supply of the bacteria is composed of complex 

 organic material built up by higher plants and animals, 

 except in the case of some soil bacteria, which are able to 

 absorb the free nitrogen of the air and use it for nutritive 

 purposes, or derive nitrogen from nitrites or nitrates. This 

 organic material must be in solution in order that it may be 

 absorbed through the cell wall. Inorganic salts are fre- 

 quently present and seem necessary for protoplasmic nutri- 

 tion and to assist in keeping up the osmotic pressure of the 

 cell, as is the case in higher plants. Most plants use very 

 simple substances for food. 



5. Certain recognized species of bacteria have the power 

 of deriving their nitrogen from the disintegration of ammonia 

 (NH 3 ) compounds. In this respect they resemble some 

 plants and differ from all animals. 



