75 



The color of the slime in the tubes 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 g-rowth was still pale 3'ellow and 

 not over one-thirtieth as abundant 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 began to ])e visible at the end of the 

 second day. That a considerable portion of the germs were injured 

 by exposure in the U tube was, however, shown by the fact that scrap- 

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

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

 broth failed to cloud them in 8 days. 



I^s. canipestris and Ps. stewarti were tested at the same time. Ps. 

 cam,pestris was grown on cylinders of flat white turnip in distilled 

 water and P^. stewaHi on similar cylinders of sugar beet, i. e., each 

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

 growth was prompt and abundant. 



In the U tube containing Ps. campestris the mercur}' had risen only 

 30 mm. in 46 hours, and there was nearly or quite as much growth 

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

 the mercury stood at 50 mm., and the growth was comparatively 

 feeble, i. e., not one-twentieth as much, as in the check. On the fif- 

 teenth day 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 began to be 

 visible the second day. A second U tube gave identical results. 



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

 15 mm. in 46 hours and there was about as umch growth as in the 

 check. At the beginning of the fourth daj' 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 much as in the check tube. At this time the color of the 

 growth in the check tube was between buff 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 tu))es 

 over one-thirtieth as nuich growth as in the check, and it was paler 

 y.'llow. In the fluid in the bottom of the check there was also a 

 copious bufi'-yellow precipitate, but there was none in either of the 

 tubes which had been in the nitrogen. Here, again, something scem-s 

 to have done injury to the organisms, for after })reakiMg the selil 

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

 days). The check was deep buft" yellow. In the tubes which had 



