88 



which h i>ale yellow, has a peculiar rougliened or areolate appearance, which 

 appears to ])e due to wrinkles extendinir in various directions. The shallow pits are 

 2 to 3 nun. in diameter. 



(3) CWn<' .sug^or.— Fully 6 times as much growth as in the check tul)e. 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, ))ut finely roughened. 



Twenty-nintli day. 



(1) CZ/rt-A-.— 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 whitening of the surface of the agar. No l)rown stain. 



(2) Graj)e 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 ])aler. 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 )<ugar.— Color uniformly pale yellow. Surface drier than it was and 

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

 translucent than in the cheek 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 l:>een 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 by some acid. 



Forty-seventh day. 



(1) Cherl:— The streak is drying out. It is (Jo l)y 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 zoogloe» and siiort, 

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

 exceedingly rare. 



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

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

 tube. It scrapes off easily and gives an acid reai'tion on neutral lituuis jjaper. A 

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

 but roughened, and wrinkled slightly in the lower part of the slant. Examined 

 microscopic-ally, the slime consists of zooglrtw, 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) Carie sugar {aiwfJwr lube of ihe same age, hut containivg onhj 6.75 per cent of 

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

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

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

 Examined microscopically, the slime consists of zoogl(e;e, numerous chains of 10 to 

 40 segments, and many single rods, i)airs, and fours joined end to end. In many of 



