40 PATHOGENIC BACTERIA. 



monas, while a similar organism of spindle shape is 

 called a spirulina. One species of spiral bacteria in 

 whose protoplasm sulphur-grounds have been detected 

 has been called ophidiomonas. 



Some of the spirilla are exceedingly long and deli- 

 cate, as the spirochaeta of relapsing fever ; others which 

 are stouter, like the spirillum of cholera, habitually occur 

 in such short individuals as to be easily mistaken for 

 slightly-bent bacilli. 



Classification. Leeuwenhoek, when he first saw the 

 bacteria and his successors even to so recent a date as 

 to include Khrenberg and Dujardin did not doubt that 

 they belonged to the infusoria. 



It was not until biologists had concluded that organ- 

 isms which take into their bodies particles of solid or 

 semi-solid material, digest that which is useful, and 

 extrude the remainder, are animals, and that those which 

 live purely by osmosis and exosmosis are vegetables, that 

 the bacteria, which we have seen provided with a resist- 

 ant cell-wall, allowing of no possibility of nutrition 

 except by osmosis and exosmosis, could be finally and 

 correctly classed among the members of the vegetable 

 kingdom. 



The extremely simple organization of bacteria naturally 

 places them among the lowest members of the vegetable 

 kingdom, in that class of the Cryptogamia known as 

 Thallophytae, comprising the algae, lichens, and fungi. 



The algae are mostly water-plants, containing chloro- 

 phyl and obtaining their nourishment from inorganic 

 substances. 



The lichens are plants, some of which contain chloro- 

 phyl. They live upon inorganic matter, which they 

 generally absorb from the air. According to the new 

 view of the subject, some, if not all, of these plants are 

 regarded as fungi growing parasitically upon algae. 



The fungi, the lowest group of all, are minute or large 

 plants, mostly devoid of chlorophyl, living upon organic 

 matter, which they obtain as saprophytes from decom- 



