59 



in 500 c. c. of H.,0). The tests were made in the usual way with 5 c. c. 

 portions of the copper sohition and 5 c. c. of the alkaline solution in 40 

 0. c. of distilled water, boiling 2 minutes in white porcelain capsules. 

 The check culture of P><. hi/acint/u was estimated to have reduced only 

 a small fraction of 1 c. c. of the copper solution. On settling- there was 

 only a little red precipitate and the fluid was still quite green-blue, so 

 that perhaps not more than one one-thousandth of the starch was con- 

 verted. The cabbage and the bean germ grew as well, or very nearly 

 as well, on the peptone-potato starch without the diastase as with it, 

 the cultures looking much alike. 



Inasmuch as the Taka-diastase contained a trace of some reducing 

 substance and the peptone in water was able of itself to nourish the 

 hyacinth germ for a time, it was thought best to repeat this experi- 

 ment, using solutions of mineral salts, sodium asparaginate and ammo- 

 nium lactate in place of the peptone, the same kind of starch, and a 

 Taka-diastase, reprecipitated for me by Dr. John M. Francis. 



Nutrient Starch Jelly No. 1. 



This medium was prepared from Uschinsky's solution, substituting 

 potato starch for the glycerine. My method of preparing this medium 

 and the following one need not be given here, as it has been published 

 in Proceedings of the American Association for the Advancement of 

 Science, Boston meeting, 1898, page 411, and in Centralblatt fiir Bak- 

 teriologie, 2. Abt., Bd. V, page 102. All that is necessary to say is 

 that each tube contained from 5 to T c. c. of the solution and 1 to 1.5 

 grams of the dry starch. After the starch had set and was ready for 

 use the check tubes were counted out and the slant surface of the jelly 

 in each of the others was flooded with 1 c. c. of distilled water contain- 

 ing exactly 20 milligrams of the diastase. These tubes were then put 

 into the thermostat at 34° C. for li hours, and afterwards the diastase 

 was destroyed and the tubes sterilized in the usual way, i. e., by steam- 

 in cf for a few minutes on 8 consecutive days. 



Before using, the diastase was carefully tested for the presence of 

 reducing substances and found to be entirely free. This diastase like- 

 wise gives no blue reaction with guaiac resin and hydrogen peroxide. 

 The starch jelly was also tested in the same way, using Soxhlet's solu- 

 tion, and was found to be entirely free from reducing substances. 

 On the contrary, bits of starch jelly from the tubes which had been 

 treated with the diastase gave an immediate rusty precipitate when 

 dropped into the boiling fluid. 



Three tubes of this medium were inoculated, along with 3 check 

 tubes. These 6 tubes were divivided into 3 lots, each group being 

 inoculated from a separate culture. All were kept in the dark at 

 room temperatures, which ranged from 19° to 25° C. during the first 

 2 weeks and then from 25° to 34° C. (mostly 25° to 29°). 



