74 



out of the water; the fluid was also heavily clouded, and there was 

 considerable pale yellow precipitate. In the other check tube growth 

 was not so abundant, but about 3^ sq. cm. of the slant surface was 

 covered with a smooth, wet-shining", pale j-ellow growth. 



The tubes were removed from the nitrogen on the fifteenth day. In 

 none of the 4 had there been any growth whatever, although there 

 was an abundance of moisture in each. Moreover, in none of them 

 did any growth subsequently appear (17 days). 



The pyrogallic acid used in this instance was a fresh supply and had 

 a peculiar penetrating smell. Whether the failure of these cultures to 

 grow after removal to the air is to be ascribed to the nitrogen or to 

 some substance emapating from the pyrogallic acid must be left an 

 open question. 



Ps. cainpestvh and Ps. steioarti were tested at the same time with 

 identical results. The check tubes grew promptly. The others (2 of 

 Ps. campestris and 4 of Ps. steivarti) made no growth whatever, either 

 while in the nitrogen (15 da^^s) or after being taken out (17 days). 

 The temperature during this experiment ranged from 20° to 25° C. 



(3) The third experiment did not fully accomplish what was intended, 

 but is perhaps just as instructive. Each U tube received a tube con- 

 taining 10 grams of an old stock of pyrogallic acid, not previously 

 used, and 20 c. c. of 5 per cent caustic potash water. It browned 

 slowly, and at the end of 48 hours a considerable part of the oxygen 

 remained unabsorbed (perhaps one-third), and meanwhile the bacteria 

 had begun to grow. The cultures were on coconut. Each tube was 

 inoculated with two 3 mm. loops of Ps. hyacinthi from a cloud}^ beef- 

 broth culture 5 days old. 



Pesult. — The check tube grew prompth\ During the first 16 hours 

 the bacteria in the two tubes in the nitrogen (+ some oxygen) made 

 about one-half as much growth as in the check tube. The column of 

 mercury was now 40 mm. high. There was some additional growth in 

 these tubes on the third day, but it was paler yellow than in the check 

 tube. At the beginning of the fifth day the mercury stood at 58 mm. 

 and the oxygen was probabh^ all absorbed. From this time on there 

 was no increase in growth. On the fifteenth da\^ the seal was broken 

 and the tubes removed for a more careful examination. The pale jqI- 

 low growth in each tube was not more than one-twentieth as much as 

 in the check tube. 



The results were much the same in another U tube. At the end of 

 the second day the mercury stood at 35 mm. At the beginning of the 

 fifth da}^ it had reached 59 mm. During this very gradual absorption 

 of the ox^^gen there was some growth, but it was less than in the check 

 tu})e (not over one-fifth as much), and it ceased after this date. The 

 color of the slime in the check tube at this time was canarv vellow. 



