48 Report op the Bacteriologist of the 



dishes it gives a broad surface for inoculation. A flamed needle 

 touched to one of the red spots in a cheese and then drawn re- 

 peatedly over a couple of such surfaces rarely fails to give iso- 

 lated colonies of the desired organism. Transfers made in like 

 manner from these isolated growths to other potato slices usu- 

 ally gives quite homogeneous cultures, the purity of which may be 

 later tested upon gelatin plates and other substances. Follow- 

 ing this old method, which on account of its inconvenience has 

 been discarded by bacteriologists for a generation, pure cultures 

 have been obtained from outbreaks in a half dozen factories 

 scattered from St. I^awrence County to Allegany County. 



While the methods in use enable us to isolate the organism 

 with comparative ease from the red spots in cheese where it is 

 present in an almost pure culture they are very little use when 

 the desired form is mixed with a variety of others; as is the case 

 in samples taken from the factory and its surroundings. The 

 attempt has been made in the laboratory to perfect methods for 

 recognizing the causal organism when present in relatively small 

 quantities as would be the case in the mixed milk from the vat 

 or in the can of any patron provided it was derived from such a 

 source. Thus far these efforts have not been crowned with a 

 high degree of success. 



Fine distinctions as to the manner of growth of cultures de- 

 rived from such widely separated portions of the country will 

 not be discussed at this time but will be reserved until- work 

 upon the whole subject has reached such a satisfactory stage as 

 to justify a more extended treatment. SuflSce it to say that all 

 the cheese samples examined presented essentially the same gen- 

 eral appearance and each could clearly be referred to a biological 

 cause; so that we can feel fairly certain that we have to do with 

 a definite biological trouble spread over a wide extent of territory. 



PRODUCING RUSTY SPOT IN EXPERIMENTAL CHEESE. 



While the attempt was being made in the laboratory to devise 

 means of readily recognizing the cause of this trouble, cheeses 

 were prepared in various ways using starters derived from in- 



