EXPERIMENT STATION BULLETINS. 



453 



The first series was made in milk which was neutralized every 24 

 hours in order to obtain old cultures with plenty of cells. The Gram 

 stain was used since other methods stained the milk proteins also. 

 The averages of the duplicate counts are given in the following table: 



Culture, 24 hours old 



24 hours after first neutralization . . . 

 48 liours after second neutralization 



76 



84° 



92° 



1,280,000,000 

 1,660,000,000 



5,000,000,000 

 2,256,000,000 

 1,278,000,000 



A duplicate experiment with another strain gave the following data; 



Acidity . 



Fresh culture, 48 hours old 



24 hours after first neutralization. . . 

 48 hours after second neutralization 



64° 

 46° 

 52° 



Plate count. 



1,620,000,000 

 1,200,000,000 



Microscopic 

 count. 



2,130,000,000 



852,000,000 



1,278,000 000 



The microscopic counts are doubtless very unsatisfactory, since they 

 show a decrease in the total number which is impossible. The discrep- 

 ancy was largely due to the difference in the consistency of the sour 

 milks, the same loop holding different quantities of milk with different 

 samples. In the following set of counts 20 loops of sour milk were 

 weighed and averaged with each determination. 



Acidity . 



Plate count. 



Microscopic 

 count. 



.July 4, 24 hours culture 



July 5, 24 hours after first neutralizing. . , 

 .luly 0, 24 hours after second neutralizing 

 July 7, 24 hours after third neutralizing . , 



58° 

 60° 

 58° 

 4'i° 



650,000,000 

 1,000,000,000 

 1,480,000,000 

 2,450,000,000 



2,590,000,000 



780,000,000 



1,909,000,000 



1,985,000,000 



The average w^eights per loop on these 4 days were 1.39 mg, 2.0 mg, 

 2.32 mg, 2.00 mg. If the averages varv so much, it is very plain 

 that these figures may not represent at all the accurate weight of a 

 single loop. 



The experiment was repeated with the only difference that this time 

 the loops of milk for counting were removed after neutralization, to 

 avoid the curd which could not be broken up satisfactorily by shaking. 



