208 



Studies In Bacteriosiii 



ISOLATIOX OF THE CaUSAL OrGANISM. 



Microscopical examination of a section of the grey tissue underlying 

 the brown spot shows that the hyphae are invaded by crowds of bacteria. 

 The preparation from which Figs, 3 and 4 are taken shows the pileus 

 completely disorganised and penetration of bacteria to a depth of about 

 half a millimetre; the organisms are mainly within the cells of the 

 hyphae as is shown in Fig. 4. 



^P 



Fig. 2. Mushrooms artificially infected, cc controls. 



Eemoval with aseptic precautions of some of the bacterial tissue 

 and inoculation into mushroom-extract or other nutrient media yielded, 

 without the slightest difficulty, pure cultures of an organism which was 

 identical in every case, leaving no doubt that the causal organism had 

 been obtained. The organism was plated several times on mushroom- 

 extract agar and on bouillon-agar in order to ensure purity and from 

 the first the colonies were all of one type. 



