83 



B. roll: 



(a) Beif hnith. — July 1, Home growth; no rim or pellic^le; only the merest trace 

 of clouding and no rolling cl<iudy on shaking, but a white precipitate 10 mm. l)road. 

 July 2, well clouded; a thin white rim, and a gathering of zooglrepe into the upper 

 layers which are cloudiest. July 5, heavily clouded, more so than on the 2d; a 

 thin white pellicle and a white rim 8 mm. wide. July 9, as on the 5th; the pelli- 

 cle settles on very gentle shaking. 



(b) (rrupc sugar prptoiii' initcr wiUi inetliyJenc blue. — July 1, a slight growth; fluid 

 feebly clouded; no rim, but some slight fragments of pellicle and a precipitate 4 mm. 

 wide; fluid nearly coh^rless; on exposure to the air the fluid becomes bluish, i. e., 

 like the carrot-rot culture; the uninoculated tubes are greenish. July 2, heavily 

 clouded; there has been no reduction of the color; it is now a pure ))right blue 

 (brighter than yesterday) . July 5, well clouded; no rim or pellicle; fluid (by trans- 

 mitted light) a uniform l)right blue. July 9, as on the 5th. July 16, fluid pure 

 blue, no reduction of color; moderately cloudy, no rim, no pellicle; a scanty bacterial 

 precipitate which is blue. 



(c) Salted peptone water with rosolic add. — July 1, a rosy precipitate 3 nun. wide; 

 no clouding, no rim, no pellicle. July 2, moderately cloudy; fluid is changing to 

 pink. July 5, well clouded; no rim or pellicle; fluid deep pink; at least twice as 

 much color as in the corresponding tube of B. jjyocyaneus pericarditidis. July 9, as 

 on 5th. July 16, feebly clouded, slight precipitate; no rim or pellicle; fluid deeper 

 red than that in the corresponding tube of B. pyocyaneus-pericarditidis. 



. Growth in Carbon Dioxide. 



The carbon dioxide was prepared in quantity in a Kipp generator 

 from boiled marble chips and c. p. hydrochloric acid diluted with dis- 

 tilled water (1 part acid, \) parts water). The gas was allowed to flow 

 until all air was displaced from the apparatus. It was washed in 1 

 per cent caustic potash water and then in distilled water. The tubes 

 were exposed in a deep specimen jar with a flat brass top provided 

 w^ith inflow and outflow tubes having very perfect stopcocks. When 

 all was ready a waxed rubber gasket was laid on the top of the jar and 

 the solid l)rass top was clamped down securely. The jar was first 

 exhausted of air utitil the mercury stood at 3 inches. It was then 

 tilled with the CX)., five times, and as many times pumped out. After 

 the sixth tilling th(> stopcock was turned off' and everything sealed 

 securely. Preliminary exhaustion tests had shown onl}^ a slight leak- 

 age, i. e,, in 2-4 hours the mercury in the cistern barometer rose only 

 from 2i to 3i inches. 



The following media were tested: Tubes of beef l)roth Tieutral to 

 phenolphthaiein (stock 382); tubes of potato (stock 405); tubes of 

 coconut (stock 412); slant beef -extract peptone agar neutral to litmus. 

 Each tube was inoculated copiously and in the same way, i. e., with 

 large loops from well-clouded beef ])roth cultures 13 days old. Two 

 or more tubes of each medium were inoculated and one of each medium 

 was held as a check. The exposui'e was begun March 10 and the tubes 

 were removed to the air after 1(» days, i, e., on March 2<>, On taking 

 off the brass cover, lighted matches were repeatedly plunged into the 



