75 



The color of the slime in the tu))es from the nitrogen was paler, i. e., 

 between primrose and Naples yellow. This U tube was also opened on 

 the fifteenth day, at which time the growth was still pale yellow and 

 not over one-thirtieth as a))undant as in the check tube. 



In 8 days from the time these 4: tubes were removed from the nitro- 

 gen there was an abundant, smooth, wet-shining, bright yellow growth 

 in each tube. This new growth })egan to ))e visi})le at the end of the 

 second da3\ That a considerable portion of the germs were injured 

 b}' exposure in the U tube was, however, show n ))y the fact that scrap- 

 ings taken from the rather dry bacterial layer in each one of these 

 tubes when they were first opened and put into as many tubes of beef 

 broth failed to cloud them in 8 days. 



JPs. ca?npestris and JPs. stewarti were tested at the same time. Ps. 

 ccwipestris was grown on cylinders of Hat white turnip in distilled 

 water and I^s. steicarti on similar cylinders of sugar l^eet, i. e., each 

 one on a medium specially adapted to its growth. In the check tubes 

 growth was prompt and abundant. 



Ill the U tube containing Ps. campestris the mercury had risen only 

 30 mm. in 1:6 hours, and there was nearly or quite as nuich growth 

 in these tubes as in the check. On the beginning of the fourth day 

 the mercur}' stood at 50 mm., and the growth was comparative!}^ 

 feeble, i. e., iK)t one-twentieth as much as in the check. On the fif- 

 teenth da}^ when the seal was broken the slime had dried away and 

 there was no apparent growth in either tube. Eight days later each 

 cylinder was covered with a copious pale yellow, smooth, wet-shining 

 slime which also filled the fluid. This increased growth ])egan to be 

 visible the second da}'. A second U tube gave identical results. 



In the U tube containing Ps. stevxirtl the mercury had risen only 

 15 mm. in -iG hours and there .was about as much growth as in the 

 check. At the beginning of the fourth day the mercury stood at 50 

 mm., and the growth was now not one-fifth as much as in the check 

 tube. At the beginning of the fifth day the mercury stood at 55 mm., 

 i. e., nearly all of the oxygen was absorbed and the growth was not 

 one-tenth as luuch as in the check tube. At this time the color of the 

 grow^th in the check tube was between bufl' yellow and deep chrome, 

 that in the tubes in the nitrogen was '"pale yellow." On the fifteenth 

 day when the seal was broken there was not in either of these tubes 

 over one-thirtieth as much gi'owth as in the check, and it was paler 

 yellow. In the fluid in the bottom of the check there was also a 

 copious buff-yellow precipitate, ])ut there was none in either of the 

 tubes which had been in the nitrogen. Here, again, something seems 

 to have done injury to the organisms, for after breaking the seal 

 and exposing them to the air there was little increase in growth (8 

 days). The check was deep buff 3'ellow. In the tubes which had 



