83 



B. coli: 



(a) Beef broth. — July 1, some growth; no rim or pellicle; (jiily the merest trace 

 of clouding and no rolling clouds on shaking, l)ut a white precipitate 10 mm. l)roa4,l. 

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

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

 thin white pellicle and a white rim 3 mm. wide. July 9, as on the 5th; the pelli- 

 cle settles on very gentle shaking. 



(b) Grape sugar jieptaue water vAtli metliijlene blue. — July 1, a slight grcjwth; fluid 

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

 wide; fluid nearly colorless; 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 bright blue 

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

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

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

 precipitate which is blue. 



(c) Salted peptone water with rosolic acid. — July 1, a rosy precipitate o mm. ^dde; 

 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. pyocyaneus pericarditidis. July 9, as 

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

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



Growth in Garbox Dioxide. 



The carbon dioxide was prepared in quantity in a Kipp generator 

 from boiled marble chips and c. p. hj^drochloric acid diluted with dis- 

 tilled ^Yater (1 part acid. 9 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 tulles 

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

 with inflow and outflow tubes having very perfect stopcocks. When 

 all was read}^ a waxed rubber gasket was laid on the top of the jar and 

 the solid brass top was clamped down securely. The jar was flrst 

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

 tilled with the CO.^ five times, and as many times pumped out. After 

 the sixth tilling the stopcock was turned oft' and everything sealed 

 securely. Preliminary exhaustion tests had shown only a slight leak- 

 age, i. e., in '■l^ hours the mercury in the cistern barometer rose only 

 from 2i to 3^ inches. 



The following media were tested: Tubes of beef broth neutral to 

 phenolphthalein (stock 382); tubes of potato (stock -105); tubes of 

 coconut (stock 412); slant beef-extmct peptone agar neutral to litnuis. 

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

 large loops from Avell-clouded beef broth cultures 13 days old. Two 

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

 was held as a check. The exposure was begun March lo and the tubes 

 were removed to the air after Ki days, i. e., on March 20. On taking 

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



