1 86 Journal of Agricultural Research voLxviii, no. 4 



Nestler's reagent was used for the ammonia test. The maltose and 

 lactose cultures gave a fair positive reaction; the other carbohydrates 

 gave a very weak test for ammonia. 



Titration of sodium chlorid. — Tubes of neutral, peptonized beef 

 bouillon, containing, respectively, 0.5, i, 1.5, 2, 3, and 4 per cent chemically 

 pure sodium chlorid, were inoculated from 5-day-old potato agar cultures. 

 In about a week there was fair clouding in the 0.5 per cent and the i per 

 cent strengths. No growth occurred in any other tubes. 



Optimum reaction and toleration limits. — Peptonized beef bouillon 

 was used for this test. Hydrochloric acid was the acid employed and 

 sodium hydrate was the alkali. Bouillons were prepared, titrating 

 + 25, +22, +20, +18, +15, +10, +5, o, -5, -10, -20, and -25, 

 and were inoculated as uniformly as possible from 6-day-old potato agar 

 cultures. At the end of 48 hours growth was visible in + 18, + 15,+ 10, 

 + 5, and o; and in a week growth Vv^as very good in these cultures, with 

 a light flocculent pellicle. Browning, working down from the top, began 

 in these from the seventh to the ninth day, and the color continued to 

 deepen to a reddish brown (chestnut) throughout. The +10 and -j-15 

 cultures were darker in color than the + 5, and these in turn were darker 

 than those at o and +18. The + 10 culture showed heaviest growth. 

 In a month +18, +15, +10, and + 5 cultures showed no more clouding; 

 but there was a precipitate at the bottom, especially heavy in the + 10 

 tubes. This precipitate broke up readily on shaking. The o cultures 

 at this time were still cloudy, but there was also a precipitate which broke 

 up easily on shaking. 



Growth developed slowly in the —5 reaction, browning also taking 

 place more slowly than with the other cultures. A light, flocculent 

 pellicle developed in some cultures. In a month these tubes showed 

 various shades of brown, but they were no longer cloudy. There was a 

 precipitate which broke up on shaking. 



Slow growth took place in two tubes of + 20, which also turned chestnut 

 color in about a month, though they still remained slightly cloudy. 

 There was a heavy precipitate which was easily broken up on agitating. 



None of the other reactions showed growth. 



Apparently, therefore, + 10 Fuller's scale seems to represent the opti- 

 mum reaction 



Fermi's solution. — Tubes of Fermi's solution inoculated from young 

 potato agar cultures developed good clouding in 4 days. A flocculent 

 pellicle began to form in about a week and was heavy in 14 days. Slight 

 fluorescence appeared in about 2 weeks and later became fairly decided. 

 The pellicle began to settle in about 5 weeks; and finally there was a 

 heavy, flaky, and somewhat stringy precipitate at the bottom of the 

 cultures. 



Uschinsky's solution. — Inoculation was made from young potato 

 agar cultures. Clouding was apparent in 4 days and was heavy in 6 



