DIV. I 



THALLOPHYTA 



375 



was discovered by R. KOCH. It occurs in the intestine as short curved rods with 

 a single polar flagellum, and sometimes in longer spirally-wound chains. 



FIG. 299. Stained preparations from Ziegler's Text-book of Pathology, a. Gonococci in the 

 gonorrhoeal discharge, mucus and pus corpuscles with cocci (methylene blue and eosin), x 700 ; 

 b, tubercle bacilli in sputum of phthisis (fuchsin and methylene blue), x 400 ; c, splenic fever 

 bacilli in the pustule of the disease (methylene blue and vesuvin), x 3-30. (From A. FISCHER, 

 Varies, fiber Bacterieit.) 



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

 harmless occurring on the mucous membranes, in the mouth (Fig. 80), or the 

 intestine. Sarcina ventriculi, which 

 occurs as packets of cocci in the stomach 

 and intestine of man, will serve as an 

 example of these. 



In addition to saprophytic and para- 

 sitic Bacteria, there are others which, 

 though possessing no chlorophyll, obtain 

 their food from inorganic compounds 

 only. These are the Nitrite Bacteria 

 (Nitrosomonas) and the Nitrate Bacteria 

 (Nitrobactcr), which live in the soil. The 

 former oxidises ammonia to nitrous acid, 

 and the latter oxidises the nitrous to 



nitric acid. They both obtain their carbon from carbonic acid, and thus derive 

 their food independently of any organic food-supply (Fig. 300, cf. p. 254). 



FIG. 300. Nitrifying bacteria, after WIXO<;RAD- 

 SKY. o, Nitrosomonas europaea, from Zurich ; 

 b, Nitrosomonas jai-anensis, from Java ; c, 

 Nitrobucter, from Quito, (x 1000. From 

 FISCHER, Vorles. iiin-r Bactfricn.) 



Order 2. Triehobacteria. FILAMENTOUS BACTERIA ( 9 ) 



The filamentous bacteria comprise only a few genera. They approach in their 

 organisation the filamentous Cyanophyceae and may, in part at least, have been 

 derived from these as colourless forms. The majority live saprophytically in water 

 but some are autotrophic. 



The widely distributed Cladothrix dichotoma is morphologically the highest 

 among these. It is found in stagnant water, and consists of falsely - branching 



2 Bl 



