[HARRISON & barlow] SLIME-PRODUCING ORGANISM 119 



Before the green-blue color faded it could be changed to vinous by 

 adding an excess of acid and the vinous to green-blue again by an excess 

 of alkali, or the piece of agar might have different colors in concentric 

 zones. 



Magnesium sulnhate changed the blue of the agar to intense violet 



All the changes were rapid, occupying only a few minutes. The 

 colors were transparent and the bits of agar glowed with color like gems 

 — sapphire, amethyst, or emerald, according to the reagent employed. 



The Nature of the Slime. — A culture was made on the surface of 

 sucrose-peptone-agar in a large glass chamber. In a few days the 

 whole mass of the medium was coloured dark blue and the surface was 

 covered with a layer of mucous-like groA\i;h. 



The slimy growth was strained off and to 50 c.c. of it was added 

 50 c.c. of 95^ alcohol. Part of the pigment went into solution and this' 

 blue and wine coloured solution was used in studying the nature of the 

 pigment. Most of the slime separated and collected above the coloured 

 liquid, it was removed, shaken with excess of alcohol, and thrown down 

 by means of the centrifuge. So prepared, the gum was a fibrous, pasty, 

 but viscous mass, which dissolved readily in cold water, the solution 

 drawing out in threads as before. After heating the solution with 

 dilute acid it reduced Fehling's solution. 



Slimy cultures on agars, in milk, in bouillon and in Dunham's 

 solution all lost their faculty of drawing out in threads if the cultures 

 were boiled for a minute or two. A temperature lower than 98° C. 

 did not accomplish this. Strong alcohol precipitated the gum from 

 boiled solutions and on redissolving the precipitated gum in cold water, 

 the solution could be dra^ra out in threads. 



Soluble Invertase. — Invertase was produced in media without sugar. 

 Cultures in bouillon and Dunham's solution were used in this test. 



20 grams of sucrose were dissolved in distilled water, ,1 c. c. of 

 creosote was added and the volume made up to 30 c. c. by adding dis- 

 tilled water. To each tube containing about 10 c. c. of culture there 

 was added 3 c. c. of the cold sugar solution. Thus each culture con- 

 tained about 30^ of sucrose and each received 1/10 c. c. of creosote. 

 Each tube was shaken and a small amount was poured into an evaporat- 

 ing dish and boiled with a few drops of Fehling's solution; there was 

 no reduction. All the tubes were then placed upright in a water bath, 

 kept at a temperature of 52.50 C. during the first five hours, then 

 51.50 C. during the next half hour, after which the flame was removed 

 and the bath cooled gradually over night. 



After 2 hours and 10 minutes at 53 °C., the tubes were all tested, 

 and showed no perceptible reduction with Fehling's solution. All were 



