i83 MICRO-ORGANISMS AND DISEASE [chap. 



2. Bacillus mesentericus vulgafus, potato bacillus (Loffler). — 

 This bacillus is spore forming, aerobic, very motile, and is 

 thicker than the former (bacillus subtilis) ; it occurs singly or 

 in chains of two or more rods ; it and its spores have a 

 wide distribution ; it is common in dust of air, and in many 

 putrid organic substances (potato, milk) ; in milk and other 

 organic fluids that have been exposed to air contamination 

 it is often present. 



It differs from bacillus subtilis, first, by the greater thick- 

 ness of the bacilli, and, secondly, in the aspect of its colonies 

 in gelatine plates : these being round, liquefying, and con- 

 taining in the centre a membrane-like accumulation, but no 

 radiation of fibres. Sown in broth and incubated at 37° C, 

 it forms already in twenty-four hours a conspicuous, coherent, 

 wrinkled pellicle, the broth remaining limpid. The pellicle 

 is a network of filaments in which oval glistening spores 

 soon make their appearance ; the spores are of the size of 

 those of hay-bacillus, but slightly thicker. On potato it 

 forms rapidly a sticky, greyish-yellow mass, on nutrient Agar a 

 wrinkled membranous growth; growing on the surface of 

 gelatine, it Hquefies this rapidly, forming, however, a coherent, 

 wrinkled, membranous mass. 



3. Proteus vulgaris (Hauser). — This is an aerobic motile 

 non-sporing bacillus which, as Hauser has shown, is the 

 microbe of putrefaction. It is found in all putrid organic sub- 

 stances ; it is the principal microbe which is found in the putrid 

 bodies of dead animals and man. It is present normally in 

 the large intestine and from here after death soon extends 

 (grows) through the walls of the intestine into the abdominal 

 cavity, into the abdominal organs, then into the thoracic 

 viscera, and through the blood-vessels into all other parts. 

 It rapidly liquefies gelatine, and peptonises and destroys 

 animal matter. In gelatine plates (at 20° C.) its colonies 



