48 REPORT OF THE BACTRPRIOLOGIST OF THD 
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. Lawrence 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. Suffice 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- 
