88 



which is pale yelloM", has a pecuhar roughened or areolate appearance, which 

 appears to he due to wrinkles extending in various directions. The shallow pits are 

 2 to 3 mm. in diameter. 



(3) Cane sugar. — Fully 6 times as much growth as in the check tuhe. The pen- 

 holder can not be seen under it. Color pale yellow, a little paler than in the check 

 tube. Surface not smooth as in the check tube nor wrinkled as on* the grape-sugar 

 agar, Ixit finely roughened. 



Twenty-ninth, day, 



(1) Check. — Little change. The streak is 3 to 6 mm. wide. Its surface is smooth 

 and wet-shining, and to either side, on the lower part of the slant, there is a slight 

 chemical M'hitening of the surface of the agar. No brown stain. 



(2) Grape sugar. — About 4 times as much growth as in the check tube. The 

 bacterial layer covers all but the upper part of the slant and there is some growth 

 between the agar and the walls of the tube. Growth the same shade of yellow as in 

 the check tube, or only a trifle paler. No brown stain. No whitish chemical film 

 on the agar beyond the streak. Surface wet, but not smooth as in the check tube. 

 The extreme upper part of the streak is still composed of separate colonies, and the 

 rest of it is areolated i. e., covered with tiny ridges and depressions. 



(3) Cane sugar. — Color uniformh' pale yellow. Surface drier than it was and 

 slightly roughened, but not coarsely areolate, as on the grape sugar agar. Streak less 

 translucent than in the check tube, i. e. almost opaque. No brown stain. The cul- 

 ture has a feeble smell. On boiling the contents of this tube for one minute in 

 Soxhlet's solution there was a very heavy precipitate of copper oxide. Sugar and 

 agar had both been tested for reducing substances previous to inoculation and neither 

 one gave any trace of copper oxide on boiling two minutes in Soxhlet. The slime 

 remaining in the tube was very feebly alkaline to litmus, i. e., much less alkaline 

 than might have been expected from the amount of growth. This is presumptive 

 evidence that most of the alkali had been neutralized l)y some acid. 



Forty-seventh, day. 



(1) Check.— The streak is drying out. It is 65 by 3 to 6 mm., i. e., it has spread 

 but little. It is still smooth, wet-shining, and so translucent that a penholder can 

 be seen through it. The streak has well-defined margins, beyond which the surface 

 is feebly whitened. On neutral litmus paper the saffron-yellow slime has an alka- 

 line reaction. Examined microscopically, this slime consists of zoogloese and short, 

 slender rods, single or in pairs. Rods in fours are rare, and chains are short and 

 exceedingly rare. 



(2) Grape sugar. — The bacterial layer is gallstone yellow. It now covers almost 

 the entire slant (70 by 16 mm.), and is about 20 times as abundant as in tlie check 

 tube. It scrapes off easily and gives an acid reaction on neutral litmus paper. A 

 few separate colonies persist on the upper dried-out part. The surface is not smooth, 

 but roughened, and wrinkled slightly in the lower j^art of the slant. Examined 

 microscopically, the slime consists of zoogloe?e, chains, and short, slender rods, 

 single, in pairs, or in fours. Chains of 10 to 20 or more segments are numerous. In 

 some the individual segments are easily discernible, in others not. Apparently 

 some of the rods are motile. No spores. 



(3) Cane sugar {another tuhe of the same age, hut containing onli/ 6.75 per <y»/ of 

 sugar). — Growth dense and finely roughened (fine wrinkles under the liand lens). 

 No brown stain. No crystals. No chemical film. At least 10 times as much gnnvth 

 as in a check tube. Slime, buff yellow (R. VI-19), acid to neutral litnnis paper. 

 Examined microscopically, the slime consists of zooglce?e, numerous chains of 10 to 

 40 segments, and many single rods, pairs, and fours joined end to end. In many of 



