90 



RENEWED EXPERIMENTS WITH FRUCTOSE. 



The fructose (Schering's diabetine) was lirst titrated with caustic 



soda and litmus to determine its acidit}'. This was such that 10 c. c. 



N . "^ ■ 



of yq NaOH were required to render 10 grams moderately alkaline 



to litmus. One-half c. c. of this thick alkaline sirup was then pipetted 

 into 7 c. c. of Dorsett's agar for one experiment and 1 c. c. of the sirup 

 into 10 c. c. of the agar for another experiment. The agar was then 

 resterilized and slanted in the usual way. The check tubes had been 

 slanted longer than the others and their surface was somewhat dry. 

 All were inoculated with Ps. hyacirtthi from a slant agar culture 2-1 

 days old, in the same way and with approximately the same amount of 

 material. 



Second day. 



(1) Check. — A feeble growth in the form of scattered colonies. 



(2) Fruit sugar {one-half c. c. sirup). — A feeble growth, which was visible sooner 

 than in the check tube, i. e., within 18 hours. 



(3) Fruit sugar {1 c. c. sirup). — A very slight growth, not one-fourth as much as in 

 the preceding. 



Fourth, day. 



(1) Check. — Not a good growth. It occurs colony-wise over the streak. This agar 

 had been slanted a long time and the surface was becoming too dry for good growth. 



(2) Fruit sugar [one-half c. c. sirup). — A distinct multiplication during the last 48 

 hours, but not yet a homogeneous streak, i. e., growth thin in some places and more 

 abundant in others. Not yet more growth than would have appeared in the same 

 time on a freshly slanted check tube. 



(3) Fruit s-ugar {1 c. c. sirup). — Very little growth, i. e., not one-twentieth as much 

 as in the preceding. This substratum evidently retards growth. 



Seventh, day. 



(1) Check. — A much better growth. The colonies touch or nearly touch, forming 

 a thin, distinctly yellow slime over nearly the whole slant. 



(2) Fruit sugar [one-half c. c. sirup) . — There is now more growth than the agar alone 

 would give. The streak is dense and rather abundant (47 by 10 mm. ), pale yellow, 

 smooth, and wet-shining. 



(3) Fruit sugar [1 c. c. sirup). — Growth very feeble. There has been a slight increase 

 during the last 3 days, but the growth is not now one one-hundredtli, })erhaps not 

 one one-hundred-and-fiftieth, as much as in the preceding tube. 



Twelfth day. 



(1) Check. — The colonies, for the most part, have now fused into a smooth surface. 



(2) Fruit sugar [one-half c. c. sirup). — A very copious, pale yellow, smooth, Avet- 

 shining growth covers the whole slant, and is growing in l^etween the tube and the 

 agar. At least 4 times as much growth as in the check tube. 



(3) Fruit sugar [1 c. c. sirup). — The restraining influence is being overcome. About 

 one-third as much growth as in the preceding, and excellent where it has obtaine<l a 

 foothold. This growth is of the same character as in the preceding. 



