ent methods of culture. Control microscopic examinations of the cheese were 

 frequently made to determine if there were in them any forms which did not 

 develop in the culture plates. No forms were found, however, except those 

 which developed in the cultures. 



The medium used for the culture o; the bacteria contained in the cheese 

 from the Carp factory was the ordinary beef-ipeptone-gelatine (12 per cent.). 

 Agar proved entirely unsuitable for the requirements of the investigation. The 

 cultures were made aerobically, the few cultures made anaerobically not show- 

 ing the development of any forms except those found in the ordinary plates. 



The medium used for the Guelph cheese was peptone-whey gelatine (10 

 per cent.), with or without the addition of blue litmus, precipitated chalk, or 

 rosolic acid. Usually two plates were made from beef-peptone lactose gela- 

 tine. For each sample, from 5 to 7 plates were made. 



Kingston Method. 



As the methods followed at Kingston were somewhat different from those 

 used at Guelph, we shall briefly outline them. 



The Kingston Method. Usually one-tenth gram of the interior of the plug 

 was taken and thoroughly pulverized in a sterile mortar with coarse granu- 

 lated sugar. The sugar had been previously sterilized by soaking under ether 

 for 2 to 7 days and then carefully evaporating the ether. 



The finely pulverized mass was then washed with a measured amount of 

 sterile water into a sterilized shaking bottle, and this was kept constantly 

 agitated so as to secure a thorough and even admixture. The amount of 

 dilution required varied with the age of the cheese. It was found that for 

 green cheese a dilution of one part of cheese in from 20,000 to 100,000 parts 

 of sterile water was required. This dilution was commonly effected as fol- 

 lows: 100 cc. of water were used to dissolve the powder and wash it into the 

 first sterile shaking bottle. After this bottle had been thoroughly agitated for 

 at least three minutes, 5 cc. were quickly removed with a sterile pipette and 

 added to a second shaking bottle. To this was then added as many cc 's as 

 would make the dilution required. By this means one avoided the use of a 

 large amount of diluting fluid. From the second bottle, after prolonged agita- 

 tion, measured quantities were quickly added to melted gelatine After a 

 careful admixture with the gelatine culture was secured, plates were poured in 

 the usual manner. These plates were incubated at from 21 to 22 degrees C, 

 till all development had ceased. The colonies which had developed were then 



Toltt-ri-tr"' '\ •"'"' '"'■'^"- °' ^'^ '^"^^"^^ P^^^^^' -d the various 

 colonies identified as to their species. Repeated sub-cultures in various media 



