CONTINUED: CLASSIFICATION. 165 



allowing it to stand for several days. Bacillus tetani occurs in the soil, on 

 old rusty nails, etc. It is called the tetanus bacillus because it causes a 

 permanent spasm of certain muscles, as in "lockjaw." This bacillus 

 grows and produces this result on the muscles when it occurs in deep and 

 closed wounds such as are caused by stepping on an old nail or other object 

 which pierces the flesh deeply. In such a deep wound oxygen is deficient, 

 and in this condition the bacillus is virulent. Opening the wounds to 

 admit oxygen and washing them out with a solution of bichloride of mer- 

 cury prevents the tetanus. Many bacteria are of great importance in bring- 

 mg about the decay of dead animal and plant matter, returning it to a con- 

 diti'v* for plant food. (See also nitrate and nitrite bacteria, Chapter IX.) 

 While rtrost bacteria are harmless there are many which cause very serious 

 diseases of i/ian and animals, as typhoid fever, diphtheria, tuberculosis, etc., 

 while some others produce disease in plants. Others aid in certain fer- 

 mentations 01 liquids and are employed for making certain kinds of wines 

 or other beverages. Some work in symbiosis with yeasts, as in the kephir 

 yeast, used in ferm-<?rumg certain crude beverages by natives of some coun- 

 tries. 



357a. Myxobacterial-s ^yxobacteriaoeee Thaxter *). These plants con- 

 sist of colonies of bacteria-like organisms, motile rods, which multiply by 

 cross-division and secrete a gelatinous substance or matrix which surrounds 

 the colonies. They form plasm odium-like masses which superficially 

 resemble the slime moulds. In the fruiting stage some species become 

 elevated from the substratum into cylindrical, clavate, or branched forms, 

 which bear cysts of various shapes containing the rods in a resting stage, 

 or the rods are converted into spore-like masses. Ex., Chondromyces 

 crocatus on decaying plant parts, Myxobacter aureus on wet wood and 

 bark, Myxococcus rubescens on dung, decaying lichens, paper, etc. 



Class Flagellata. 



358. The flagellates are organisms of very low organization resembling 

 animals as much as they do plants. They are single celled and possess two 

 cilia or flagella, by the vibration of which they move. Some are without a 

 cell wall, while others have a well-defined membrane, but it rarely consists 

 of cellulose. Some have chromatophores and are able to manufacture 

 carbohydrates like ordinary green plants. These are green in Euglena, 

 and brown in Hydrurus. Some possess a mouth-like opening and are able 

 to injest solid particles of food (more like animals), while others have no 

 such opening and absorb food substances dissolved in water (more like 

 plants). The Euglena viridis is not uncommon in stagnant water, often 

 forming a greenish film on the water. 



* See Bot. Gaz., 17, 389, 1892. 



