87 



(4) Growth on vegetables rich in grape sugar or cane sugar was 

 copious and long continued. These two sugars are excellent foods, 

 and when not present in such excess as to inhibit growth (pro))ably by 

 plasuiolysis) they greatly favor the multiplication of this organism. 



Sugar Gelatin. 



(See Grow^th on solid luedia.) 



Sugar Agars. 



Some interesting results were obtained by adding large doses of 

 sugar to 10 c. c. portions of Mr. Dorsett's +15.5 meat-extract peptone 

 agar (see Grow^th on solid media) and growing on it the various yellow 

 organism in slant cultures. Their behavior on these media was always 

 compared with that on check tu))es of the sugar free agar. 



NINE PER CENT SUGARS. 



First series. 



Agar recently tubed and slanted (10 cc. to 1 gram of the sugar) . Inoculations with 

 Ps. hyacintJti, using bright-yellow slime from a starch jelly culture 28 days old. All 

 the inoculations were made in the same way and with approximately the same 

 amount of material. 



Third day. 



(1) f'lierk. — Streak 2 by 75 mm., distinct the whole length of the track, best devel; 

 oped at the lower end, where it is distinctly pale yellow. In the middle 3 c. m. it 

 consists of separate colonies. 



(2) Grape sugar {1 gram of 3ferck's c. ]>. anhydrous). — Streak invisible except in 

 a very favorable light, where it looks like a colorless film. 



(3) Cane sugar {1 gram of white commercial). — A thin pale yellow growth over 

 the whole slant. In strong contrast with the grape-sugar agar. Also more growth 

 than in the check tube. 



Seventh day. 



(1) Check. — The streak is now 3 to 5 nun. wide. All of the colonies have fused 

 into a smooth, yellow, wet-shining homogeneous surface. 



(2) Grape sugar. — (irrowth mostly in the form of separate colonies and less than in 

 the check tube — i. e., a distinct retardation. There are many of these colonies, and 

 where they have coalesced the color is about the same shade of yellow as in the 

 check tube. 



(3) Cane sugar. — Tlie whole surface of the slant agar is covered and hidden by a 

 copious pale yellow growth. Six times as much growth as in the check tube and 8 

 or 10 times as much as on the grape-sugar agar. 



Sixteenth day. 



(1) Chcrk. — The streak has not widened any. It is smooth, translucent, wet- 

 shining, and distinctly pale yellow. The margins of the streak are thin but distinct. 

 A penholder is plainly visible under the streak. 



(2) Grape sugar.— (yvowih. has quadrupled and is now about 3 times as abundant 

 as in the check tube, but its surface is very unlike that of the latter. The surface, 



