484 



STATE BOARD OF AGRICULTURE. 



Tn Tests Nos. I to VI inclusive, litmus lactose agar having calcium 

 carbonate in suspension, was used for plating. 



TABLE I. 



DIFFERENTIAL COUNTS ON LITMUS LACTOSE AGAR + CaCO 3 



Number of test. 



Age of combined culture. 



Acidity of 



culture at 



time of 



estimate. 



Number of bacteria in each 



cubic centimeter of milk 



at the times specified. 



B. typhosus. 



Bad. ladis 

 acidi (Joh.) 



■ { 



II 



1 



■V { 



V 



VI 



hours. . 

 22 hours . . 



hours. . 

 16.5 hours 

 19 hours . . 



hours. . 

 17f hours. 

 22i hours. 

 40J hours . 



hours . . 

 22} hours . 



hours . . 

 43 hours . . 

 48 hours . . 



hours. . 

 18i hours. 

 23i hours . 



15° 



67° 



15° 



49° 

 59° 



15° 

 57° 

 66° 

 73° 



15° 

 60° 



15° 

 75° 



76° 



15° 

 69° 

 79° 



181,688 

 1,000,000 



3,750.000 

 2,375,000 

 2,800,000 



1,260,850 



1,375,000 



20,000 



None. 



3,375,000 

 1,100,000 



86,250 

 None. 

 None. 



325,415 



5,500,000 



None. 



20,688 

 717,500,000 



1.30,000 



65,575.000 



136,675,000 



149.625 



112,470.000 



25,200,000 



6,675,000 



134,125 

 229,170,000 



328,540 



136,7.50,000 



49,000,000 



a51,.500 

 095,500,000 

 166,470.000 



From the counts recorded above, it may be concluded that the acid 

 produced by the lactic organism has an inhibitive influence upon the 

 typhoid bacteria. The conditions, however, under which this experiment 

 was performed were not wholly satisfactory, and the above conclusion 

 can not be deemed as final. 



The litmus lactose agar containing calcium carbonate was not wholly 

 satisfactory as a differentiating medium because of the difficulty in 

 counting the typhoid colonies. The sub surface colonies were oftentimes 

 scarcely discernible on account of the suspended particles of the calcium 

 salt. The surface colonies of B. typlwsiis were moist, translucent and 

 bluish rendering them, also, seen with difficulty. 



Experhnent II. ■ , 



BILE SALT MKDIUM. 



In water analysis, a bile salt medium is often used for differentiating 

 B. typhosus and B. coll. McConkey^ states that "Bile salt media inhibit 

 most of the organisms found in air and soil when the incubation tem- 

 perature is 37°C. aud over." ITe uses lactose in combination with the 

 bile salt to assist in the differentiation. 



Eelying on the efficiency of this medium for differentiating B. ti/phosus 

 from air, soil, and other microiirganisms, and working under the supposi- 

 tion that lactic bacteria would respond in much the same manner as 



