EXPERIMENT STATION BULLETINS. 477 



TABLE XXI. — Old Broth Cultures after Addition of Lactose: Strain II. 



Age of broth culture. 



Time after 

 adding 

 lactose. 



2 days 



4 days . 



hours. 

 16 hours. 

 24 hours. 

 48 hours. 



hours. 

 16 hours. 

 24 hours. 

 48 hours. 



6 days . 



hours. 

 16 hours. 

 24 hours. 

 72 hours. 



Bacteria per cc. 



f 7,500,000 

 1 7,800,000 



f 346,000,000 

 1369,000,000 



J 350,000,000 

 1.350,000,000 



/ 5,000,000 

 I 5,600,000 



/ 247,000,000 

 1277,000,000 



[279,000,000 

 1280,000,000 



/ 5,500,000 

 I 6,700,000 



/ 292,000,000 

 1311,000,000 



/ 397,000,000 

 1396,000,000 



Acidity. 



22.5° 

 22.5° 



45 

 46 



.5M 



.0°; 



50.5° \ 

 52.0°/ 



56.0° 1 



0°; 



56 



21 .5° \ 

 21.5°; 



42.0 

 42.5 



'°1 

 °/ 



49.0° \ 



50.0°; 



f 55.0° 1 

 I 58.0°; 



22. 

 22 



.0°1 



.0°; 



49.0° 



49.5° 



55.0° 

 55.0° 



{ 



69.5° \ 



70.0°; 



Fermenting 

 capacity. 



20.7x10 



1.8x10 



0.6x10' 



25.6xl0~ 



3.2x10 



1.0x10 



29.1x10 



1.5x10 



.10 



0.5x10 



little diflference after 2 aod 4 days, so the last flask was kept for 21 

 days. In this time, a decided decrease in the number of bacteria had 

 taken place, and the multiplication after the addition of lactose was 

 not very rapid. No acid was formed in the first 16 hours, but this can- 

 not be accounted for by a lack of fermenting capacity. The number of 

 cells is so small that the total acid produced in 16 hours could not be 

 detected by titration. It amounts to only 0.2°. From 16 to 24 hours, 

 the fennenting capacity is normal. 



The experiments show plainly the necessity of sugar for abundant 

 growth of the lactic organisms. The final number per cc. reached in the 

 absence of sugar was 7,000,000 and 20,000,000 respectively. Addition of 

 lactose raised these numbers to 350,000,000 and 600,000,000. The long 

 sojourn in sugar-free broth has very little degenerating influence com- 

 pared with the action of milk (Tables XII and XIV). 



