47 



(l2) Stock 30(\' was an old, partially evaporated flask of 286d brought 

 back to its original volume b}' adding' distilled water. Its acidity 

 was +80; i. e.. exactly 80 c. c. of ^ NaOH would have been required 

 to neutralize 1 liter, using phenolphthalein as the indicator. Stock 

 3001) was a portion of 300c diluted with an equal l)ulk of distilled 

 water, so that its acidity was reduced to +40. Stock 300a consisted 

 of ;i portion of 300c diluted with twice its bulk of distilled water, the 

 acidit}' being consequently reduced to about +27, Three tubes of 

 each stock were inoculated from an alkaline beef -broth culture 11 days 

 old. All of the tubes were kept together in feeble, diffused light, in 

 well-plugged tubes of resistant glass, at room temperatures of 20*^ to 

 23'' C. Two of each set were inoculated with large loops, the third 

 with a tiny dro}) from the tip of a needle. 



liesult. — In 300c there was no growth whatever (21 days). In 300b 

 growth was nmch retarded, the fluid remaining clear for 8 days, and 

 probably for a much longer period. On the twenty -first da}^ when 

 next examined, the two tubes inoculated b}- loop were feebl}' clouded, 

 and showed a moderate amount of 3^ellow precipitate. There were 

 also quite a good many large ^^ellowish flecks (zoogkjeae), on the walls 

 and floating in the fluid. In the tube inoculated by needle the cloud- 

 ing was veri/ feel)le, there Avas only a .s//(7//?' precipitate, and there were 

 no zooglo3?e. On the twentj^-fifth day the fluid in the needle culture was 

 neutral to sensitive neutral litmus paper, while in the loop cultures it 

 had become feebly alkaline. In 300a clouding was visible on the sixth 

 day in the loop cultures, and on the eighth day in the needle culture. 

 Here also growth was retarded, but not so long as in 300b; e. g., on 

 the twentv-first day the tube of 300a, which was inoculated by needle, 

 was about twice as cloudy, and contained ten times as much precipi- 

 tate as the tubes of 300b, which were inoculated by loop. The organ- 

 ism changed the fluids from acid to alkaline, and in the end (55 days) 

 all of the cultures were much alike. 



(3) The last experiment was repeated, more attention l)eing paid to 

 the time of first clouding in 300b. Each tube contained, as usual, 10 

 c. c. of broth, was tightly plugged, was inoculated with one loop {oese 

 2 mm. in diameter) from an alkaline beef broth culture 12 days old, 

 and was set away in feeble light at room temperatures of 19'^ to 26° 

 C. (mostly 20'=' to 21^ C. during the first 6 days). 



ReKnlf. — In 300a clouding was first visible on the sixth day, but was 

 then very feeble. In 300b the fluid remained perfectly clear for 1!) 

 days. On the twenty-sixth day, when next examined, it was feebly 

 clouded. In 300c there was never any growth (20 days). 



Pfi. eampestris^ Ps. p/iaseoli, and BacUliiH amylovorm also refused to 

 grow in 300c. On the contrary, Pn. stewarti^ inoculated from a solid 

 culture, grew in it for a long time and very luxuriant!}-, although 

 clouding did not appear until the eighth day. 



