SECT. I 



CRYPTOGAMS 



339 



splenic fever. The relatively large rod-shaped cells may be united in short 

 chains ; they form endospores in cultures in the same way as the Hay bacillus. 

 Bacillus tctani (Fig. 247, e) occurs in the soil, and is the cause of tetanus. Its 

 straight rod-shaped cells are ciliated, and grow only in the wound itself ; their 

 spores are formed in the swollen end. Bacillus influenzae, short, slender rods ; 

 Bacillus 2iestis, small, stout, non-motile rods. Loffler's Bacillus d'iphthc7-iae 

 (Fig. 247,/) consists of small rod-shaped cells sometimes thickened at one end. 

 Koch's Bacillus tuberculosis {Figs. 247, g, 248, b), which is found in all tuberculous 

 lesions and secretions, and in the sputum, is a slender, slightly curved rod ; 

 branched forms also occur. It is non-motile and does not form spores. For these 

 reasons it is grouped with some other 



species in a special family, tiie Myco- 

 bacteriaceae (^). Typhoid fever is caused 

 by the ciliated cells of Bacillus typhi 

 (Fig. 247, h) ; Bacillus coli (Fig. 247, i), 

 the colon bacillus, which is as a rule 

 harmless and always occurs in the human 

 intestine, closelj' resembles the typhoid 

 bacillus. The comma bacillus of Asiatic 

 cholera. Vibrio cholerae (Fig. 247, k), was 

 discovered by R. Koch. It occurs in the 

 intestine as short curved rods with a 

 single polar flagellum, and sometimes in 

 longer chains of spirally wound cells. 

 Spirochaete obermeieri, which consists of 

 long, thin, spirally wound filaments, 

 without flagella, but capable of motion, 



\ 

 ^ 



r 





Fig. 249.— Nitrifying bacteria, after Winograd- 

 sky. a, Nitrosomoms europaea, from Zuricli ; 

 6, Nitrosomona.'i javanensis, from Ja^-a ; c, 

 Nitrohurter, from Queto. (From Fischer, 

 V'orles. iiber Bactericii, X 1000.) 



Fig. 2S0. — A,,Myxococciis digitatus, bright red 

 fructiflcation oceuiTing on dung (x 120). 

 B, Polyangium primigeniiMn, red fruc- 

 tification on dog's dung (x 40). C, 

 Chondrmnyces apiculatus, orange fructifi- 

 cation on antelope's dung. D, Young 

 fructiliuation (x 45). E, Single cyst ger- 

 minating (x 200). (.1, B, after Quehl ; 

 C-E, after Thaxter.) 



occurs in the blood during the attacks of relapsing fever, of which it is the cause. 



Besides the above injurious parasites there are others which are more or less 

 harmless occurring on the mucous membranes, in the mouth (Fig. 4), or the 

 intestine. Harcina ventriculi, which occurs as packets of cocci in the stomach and 

 intestine of man, will serve as an example of these. 



The Bacteria included under the names Bacillus {KhizoUum) radicicola and Bac. 

 Bcycrinckii occur in the root-tubercles of Leguminosae, and, like certain other 

 Bacteria found in the soil [Clostridium Pasteurianum, Azutohactcr chroococcum), and 

 in the sea, are capable of utilising free nitrogen in their metabolism. The 

 denitrifying Bacteria which occur mi the soil and in tiie sea decompose nitrates and 

 nitrites, and liberate free nitrogen. 



Zl 



