90 



RENEWED EXPERIMENTS WITH FRCCTOSE. 



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

 soda and litmus to determine its acidity. This was such that 10 c. c. 



\ 



of j^ NaOH were required to render 10 g-rams 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 dr^^ 

 All were inoculated with Pn. hyacintkl from a slant agar culture 24 

 days old, in the same wa}' and with approximately the same amount of 

 material. 



Second day. 



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



(2) Fruit sugar {one-half e. c. sh'up). — 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. 



(Ij 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. siru})). — 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 sugar {1 c. c. sirup). — Very little growth, i. e., not one-twentieth as much 

 as in the preceding. This substratum evidently retards growth. 



Seventli 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) FVuit 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 {ic. c. sirup ) . — Growth very feeble. There has been a slight increase 

 during the last 3 days, but the growth is not now one one-hundredth, perhaps not 

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



Twelfth day. 



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



(2) Fhmit sugar {one-half c. c. sirup). — A very copious, pale yellow, smooth, wet- 

 shining growth covers the whole slant, and is growing in between the tube and the 

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



(3) Fruit siujitr {1 c. c. sirujj). — The restraining influence is being overcome. About 

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

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



