11 



form -looking-, colon^^-like aggregates. These did not dissolve readily 

 in the fluid and all the larger ones were distinctly yellow and easily 

 visible to the naked eye. The fluid had shown no acid reaction. It 

 was now alkaline, and was not brown.* 



On the fiftieth day the fluid was feebly and uniformly clouded, but 

 much clearer than it had been. It was strongly alkaline to litmus; it 

 was not ropy; there were no rolling clouds on shaking. There was no 

 pellicle. The rim was 6 mm. wide and studded with zoogloea?; the 

 largest of these were one-third mm. in diameter and yellow to the 

 naked eye; the precipitate was still bright yellow and rather copious. 



On the seventieth da}" the fluid was nearly clear, and there was no 

 brown stain in it. It had evaporated from 10 c. c. to about 6.5 c. c. 

 Eighteen days later the fluid was entirely clear. 



On the one hundred and nineteenth day there was no brown stain, 

 and large irregular crystals were present in the sediment. 



Acid Beef Broth. 



This broth was from the same stock as 286b, but no alkali was added. 



N 

 Its acidity was +25 of Fuller's scale, i. e., 25 c. c. of — NaOH would 



have been required to render 1,000 c. c. of this broth neutral to 

 phenolphthalein. It was feebly acid to good neutral litmus paper. 

 This fluid retarded growth slightly and was distinctly favorable to the 

 formation of zoogloete. The precipitate was more copious than in the 

 alkaline beef broth and was duller 3'ellow — a dirty Naples yellow. 

 The clouding began in about 72 hours, when the inoculations were 

 made with large loops from fresh fluid cultures and on the sixth day 

 when the inoculations were made with as small a quantity of the fluid 

 as could be lifted and seen on the tip of a platinum needle. Notes on 

 one of eight cultures in this medium are given below: 



Stock 286a, tube 11, February 4, 1898: Tube of resistant glass containing 10 c.c. of 

 broth inoculated at 1 p. m. with Ps. hyacinthi from an alkaline beef broth culture 

 (No. 1, January 29), which had been cloudy for three days and contained many 

 actively motile germs. Only a tiny drop on the tip of a platinum needle was put into 

 the tube, i. e., about 1/50 of a good-sized loop. February 5, clear; February 7, clear; 

 February 8, clear. [Tubes exposed to the same temperatures as the alkaline beef 

 broths.] Two check tubes of alkaline broth (286b) inoculated in the same way were 

 cloudy on the third day. This broth exerts a distinct retarding influence which is 

 especially noticeable when the dose of germs is small. 



Feljruary 9. Clear. 



Fel)ruary 10, 2.30 p. m. Very feebly clouded; some whitish flecks (zooglcese) on 

 the wall of the tube from top to bottom on one side. 



February 19. Fluid turbid from numerous whitish flecks which are easily visible 



' Throughout this bulletin "acid" and "alkaline" refer to litmus reactions unless 

 it is otherwise stated. 



