12 



to the naked eye. (No zoogla?fe visible in the two tubes of 286b held for comparison. ) 

 Rim well developed; most of its zoogloese are white, but a few are yellowish. A pel- 

 licle consisting of zoogloete held together by a film has gone to the bottom. Fluid 

 homogeneous and now feebly alkaline to neutral litmus paper; in some of the tubes of 

 this set the fluid has begun to clear a little at the top. Precipitate dirty yellow-white 

 and rather abundant. 



March 12. No new pellicle; fluid uniformly thin cloudy; no crystals. Thezoogloese 

 scattered through the fluid and lodged on the walls of the tube are very numerous, 

 i. e., fifty times as many as in the two check tubes of alkaline beef broth. They 

 consist of irregular, loose, rather large, whitish or very pale yellow-white flecks; 

 rolling clouds are also visible on shaking. The tendency to form zoogloese is much 

 stronger in this fluid than in 286b, but they also form in the latter after a time. 

 There is a thin rim of germs on the wall of the tube for a distance of 3 mm. above 

 the fluid; this rim bears several hundred small, roundish, colony-like zoogloeae, most 

 of w^hich are now distinctly yellow — all the older larger ones. In the other seven 

 tubes of this set most of this rim went down easily as a thin broken film on gentle 

 shaking. The precipitate on the bottom of the tube covers a diameter of 10 mm. and 

 is dull yellow — between wax yellow and Naples yellow. The color of the precipitate 

 in the check tubes of stock 286b is brighter, and lies between gamboge yellow and 

 chrome yellow.^ The fluid is now plainly alkaline to neutral litmus. 



April 13. Fluid nearly clear, no rolling clouds on shaking; no brown stain; moder- 

 ately alkaline to neutral litmus paper. Precipitate more copious and certainly of a 

 duller yellow than in the strongly alkaline broth. Rim of germs all of one kind, 

 i. e., not contaminated, 6 mm. wide; all of the zooglceae on it are roundish, but only 

 the older and larger ones are distinctly yellow. 



April 25. The fluid has cleared, and there is no brown stain in it; when boiled, a 

 vapor was given off which immediately blued moist neutral litmus paper. 



Salted Beep Broth. 



To determine the effect of sodium chloride upon Ps. hyacinthi the 

 following- experiment was instituted: Stock 529, which was an ordi- 

 nary 1:2 acid beef broth (containing 1 per cent Witte's peptonum sic- 

 cum and one-half of 1 per cent c. p. NaCl), was divided into two 

 parts. To one was added an additional 1 per cent c. p. sodium chlo- 

 ride, forming stock 535; the other half was held as a check. The two 

 culture fluids were then pipetted into clean test tubes of resistant glass 

 and sterilized by steaming for a few minutes on each of three consecu- 

 tive days. After some time the two sets of tubes, each of which con- 

 tained exactly 10 c. c. of fluid, were inoculated at the same time and 

 in the same way, i. e., with approximately equal numbers of bacteria 

 from a well-clouded sugar bouillon culture (No. 6, October 29). Each 

 of 6 tubes (3 of each sort) received a 2 mm. loop of the cloudy 

 broth. The other 6 tubes each received as small a drop of the 

 clouded fluid as could be seen distinctly on the end of a platinum 

 needle. The experiment began at 3 p. m. November 5, 1899, and the 

 subsequent observations were made at about the same time each after- 

 noon. The following table, in which denotes "clear," + "feebly 



^Ridgway'a Nomenclature of colors, 1st ed. 



