61 



ratio of orowth hi the 2 sets of tu))es was still {i))out the same, viz, 

 1:100. The starch was still bluish white. On the twent3^-seveiith da}^, 

 in the tubes which received the diastase, the growth covered the whole 

 surface of the slant (800 to 900 sq. mm.) with a smooth, homogeneous, 

 wet-shining, canary yellow layer, which was a))undant enough to hide 

 the substratum. There was a trace of pink in the starch, but no ])rown 

 stain. On the thirty-fifth day the starch jelly was removed from (^ne 

 of the check tubes. It was as firm and elastic as when Hrst prepared. 

 On ])reaking it into fragments and throwing it into boiling Soxhiet's 

 solution (5 c. c. standard CuSO^ 5 H,,0 solution; 5 c. c. standard alkaline 

 solution; 40 c. c. distilled water) and continuing the boiling 3 minutes, 

 the fluid was as blue as at the beginning, and the onl}" precipitate of 

 copper oxide was an extremely slight one restricted to those fragments 

 of the jellv which were inunediately under the bacterial layer. Cer- 

 tainh' not more than one one-thousandth of the starch was converted. 



(8) The experiment just described was repeated 3 months later in 

 the warmer weather of midsummer. A new stock of the medium 

 was prepared and in this case each tube received 2 gr. of the dry 

 potato starch and 8 c. c. of the nutrient mineral solution. Instead, 

 however, of converting the starch with diastase, the carbon food was 

 supplied by the addition of various sugars, alcohols, and gums. 

 No mention will be made here of anything but the check tube 

 and a tube of the same stock fortified by the addition of 500 mg. of 

 a dextrine, which contained a substance reducing Soxhlet's solution 

 but no amylodextrine and no substance reducing Barfoed's reagent. 

 Both tubes w^ere inoculated at the same time and in the same way; i. e., 

 each with a large loop of yellow slime from a fructose-agar culture 

 IT days old, but still in excellent condition owing to its having grown 

 slowh' on the start. The tubes were kept in a dark closet at room 

 temperatures ranging from 25^ to 32^ C. (30^ to 32° during the first 

 5 days). Tubes of Ps. campedrU and Ps. phamoli were also inocu- 

 lated at the same time and kept under the same conditions. 



Br.sKlf. -In the check tube of A-, liijaclntlii there was no visible 

 growth during the first 48 hours. On the third day there was a very 

 slight growth (l)arely visible), and the bluish white translucent appear- 

 ance of the starch remained unchanged. In the tube wdiich received 

 the dextrine, growth was visil)le in 48 hours, but it was still feeble on 

 the third da}^; i. e., growth was retarded. On the third day, in the 

 check tu))es of /^y. ciunpcxtrU and P.s. j}JiasroI i^ there was i?0 times as 

 nuu-h growth, and the starch jelly under the slime, to a depth of 2 

 mm., was changed to a dead, opaque white. Returning to the hya- 

 cinth germ, there was on the seventh day, in the check tube, a very 

 thin, pale yellow streak or film down the middle of the slant. In the 

 tube which received the dextrine the whoh^ surface was covered by a 



