76 



been in the nitrogen there was no buff yellow, but only a thin whitish 

 growth. These 3 tubes were each inoculated in the same way, i. e., 

 with 2-3 mm. loops from a beef-broth culture 5 daj'^s old. 



Growth in Vacuo. 



(1) The hrst test was in a partial >'acuum with the remnant of the 

 oxygen absorbed. Under the bell jar with the cultures was a beaker 

 containing 6 grams of pyrogallic acid. In this beaker was a U tube, 

 the short arm open, the long arm closed, and containing 30 c. c. of 13 

 per cent caustic potash water, with a small bubble of air at the top. 

 The size of this bubble was so regulated that its expansion would 

 begin to force over the potash water into the p3^rogallic acid when 

 four-fifths of the air was exhausted. The exhaustion was continued 

 until the mercury in the cistern barometer stood at 2i inches. The 

 stopcock was then turned and the apparatus separated from the pump, 

 well sealed, and put away in the dark. The temperature during the 

 experiment was 20° to 26^' C. 



Eight test-tube cultures of Ps. hyacinthi were subjected to this 

 experiment. Four were on coconut (stock 395), each being inoculated 

 with one loop of 3'ellow slime from tube 27, February 2. Four 

 were on potato (stock 385), each being inoculated with two loops of 

 fluid from the bottom of tube 29, February 2, after long shak- 

 ing. Two tubes of each set were placed under the bell jar and the 

 other 4 tubes were held as checks. The experiment was begun on 

 February 9 and the seal of the jar was broken February 18, at which 

 time the vacuum continued as perfect as when hrst made. 



Result. — The 4 check tubes each showed a distinct vellow growth at 

 the end of 48 hours, and this growth continued in a typical manner. 

 The 4 tubes in the vacuum showed no growth whatever at the end of 

 the ninth day, when the vacuum was broken. Twenty-four hours 

 later there was no visible growth in any of these tubes. At the end 

 of 48 hours the 2 potato cultures showed no growth; the coconut 

 cultures showed a slight yellow growth on the inoculated face. At 

 the end of the third day the coconut cultures showed two or three 

 times as nmch growth as at the end of 48 hours, but the growth was 

 still thin and did not cover all of the cjdinder, i, e., was not more 

 abundant than the growth in the check tubes at the end of the third 

 day. One of the potato cultures now showed a feeble yellow growth 

 (less than the check tube showed at the end of the second day), and 

 there was still no visible growth or graying of the substratum in the 

 other tube. Six days after removal from the vacuum there was a 

 moderately abundant bright canarj" yellow slime covering all that part 

 of the coconut cylinders which projected out of the water. One of 

 the potato cultures now contained about as much growth as the check 

 tube, while the other also showed some growth (4 sq, cm.). In other 



