252 APPLIED BACTERIOLOGY 



It consists of long, motionless filaments which sometimes 

 grow to a millimetre in length, and which may possess 

 pseudo-branches. According to Zopf, the cocci-like reproduc- 

 tive elements grow into rods, and these into fine filaments, 

 from which laij|^r the pseudo-branches are given off. This 

 apparent branching of the filaments is the distinguishing 

 generic character of the species. The sheaths of the 

 filaments are often coloured yellow, red, olive-green or 

 brown by oxide of iron. The Cladothrix dichotoma withdraws 

 iron from water, and thus fixes it, often causing obstructions 

 in iron pipes. 



Cladothrix dichotoma can be readily cultivated on in- 

 fusions of rotting vegetables and animal substances, form- 

 ing small tufts and floating masses. On gelatine plates it 

 forms small yellowish dots surrounded by a brownish halo 

 which extends more and more over the gelatine. On 

 reaching the surface it appears as a small brownish button 

 surrounded by a very brown halo, and a depression due to 

 the slow liquefaction of the gelatine. On agar it grows at 

 35° C, as a thick shining expansion, which adheres so 

 closely to the medium that it is impossible to remove it 

 without carrying away some of the agar. The growth has 

 a tendency to form concentric rings. Sometimes the growth 

 becomes covered with a grayish efflorescence, which is dry 

 and very brittle. The agar becomes brown in colour. All 

 the cultures have a very strong mouldy smell. 



PROTOZOA. 



A number of organisms have been noticed by various 

 observers in the blood of both man and the higher animals; 

 they occur associated with a number of diseases, but they 

 often occur in the healthy subject. These organisms 

 belong to the animal, and not the vegetable, kingdom. 



