
CLASSIFICATION OF DATRY BACTERIA. 39 
No. 100. B. aureus lactis JT. (n. sp.) 
Morphology, a bacillus, size, .54 by .7u. No chains, though two or three 
adhere together. 
Gelatin plate; a bead with a smooth edge and a dark center is produced, 
1.5 mm. in diameter, which, after a few days, becomes decidedly yellow. 
Gelatin stab, a slight needle growth, with an irregular, opaque, white surface 
growth, not very thick. 
Agar; smooth, whitish growth, which, after a few days, acquires a lemon 
color, and later a Naples yellow color. 
Potato; an abundant growth, which is at first white, or slightly CO and 
quite thick, later becoming decidedly yellow. 
Bouillon, a thick, tenactous scum is produced, which sinks in the form of 
flakes, and produces a sediment. 
Milk, no effect produced on milk, except that a slight slimy scum sometimes 
appears. Butter made from cream ripened with this organism has a prominent 
flavor, which is not normal and unpleasant. There is a slight and tolerably 
pleasant aroma. The butter on the whole is of a good quality. Nos. 205 and 
100 are perhaps the same. 
No. 1387. 
Morphology, a bacillus, size, .6u by 1.2m, or occasionally larger, with round 
ends. 
Gelatin plate, the deep colonies are round and slightly granular. On the 
surface they spread into a thin, transparent colony, which later becomes thicker 
and brown and yellowish. It may occasionally form a thick, yellowish bead. 
Gelatin stab; a moderate needle growth, with a yellowish irregular surface 
growth, with a slightly raised edge. 
Agar, a not very abundant dull yellow growth. 
Potato; spreads over the surface of a thin, decidedly yellow growth. 
Milk; commonly curdled at room temperature in about two weeks, though 
sometimes becomes simply slightly lumpy. At body temperature it curdles 
completely, though the curd is rather soft. The action is amphoteric, and 
there is no digestion. No effect on butter. 
No. 78. (See Group V.) 
GROUP IV. CHROMOGENIC TYPE. (LEMON YELLOW.) 
Nos. 48 and 116. 2B. lactis erythrogenes, Varieties I. and II. 
These two cultures I regard as varieties of 2. lactis erythrogenes, although one 
is a typical bacterium and the other a coccus. Variety I. appears to agree with 
B. lactis erythrogenes of Hueppe. They have each been found several times 
and differ from each other in a few constant characters. But since the few 
differences remained constant with cultivation, I have found it convenient to 
separate them as Varieties I. and II. Variety I. liquefies gelatin very slowly, 
or not at all, while Variety II. liquefies rapidly. Variety I., moreover, does not 
grow on potato, and turns milk red; while Variety II. grows on potato, form- 
ing an abundant yellow growth, but it does not turn milk red. The characters 
of Variety II. are as follows: 
