
CLASSIFICATION OF DAIRY BACTERIA. 377 
Nos. 118 and 104. Micrococcus varians lactis. (n. sp.) 
This is one of the most common of our dairy species, being found very com- 
monly in milk and cream. It is frequently found in plates made by collecting 
dust that falls from the body of the cow during milking. | It is a very widely 
variable species.* Its power of producing pigment varies from a deep orange 
to a pure white. It commonly liquefies gelatin rapidly, but some cultures have 
been found with this power only slightly developed and some in which it is 
wholly absent. In the table I have included two of the extreme types, and the: 
variations are mentioned below. 
Morphology; a coccus form, slightly variably in size, but about Ip in 
diameter. It never forms chains, and stains easily. 
Motility; none. 
Temperature, grows readily at ordinary temperature. Grows rapidly at a 
temperature of 38°, but with less color. 
Mica plate; grows under the mica plate, but not much in the middle. Evi- 
dently an aerobe with slight anaerobic powers. 
Gelatin plate; colonies at first forming a whitish or yellowish bead on the 
surface, which sinks into a slight pit with an irregular edge. The pit broadens, 
liquefying the gelatin rapidly, and the- colony breaks up into irregular yellow 
masses. The pit is sometimes very deep, and contains the irregular floating 
masses of bacteria. The general character of the colony is very characteristic, 
and can be readily distinguished at a glance from other liquefying colonies. 
The non-liquefying variety, No. 104, simply forms a yellow colony, not 
characteristic. 
Gelatin stab, a broad, shallow funnel is produced, with a broken yellow scum 
and a yellow flaky sediment. Sometimes there is liquefaction along the needle 
track, and sometimes not. The liquefaction is rapid, and ina few days the 
gelatin is completely liquefied. No. 104 forms a shallow, dry pit, with a dense 
yellow surface growth. — 
Agar, a very characteristic, dry, rough, yellow growth. The color is slightly 
orange, though not very deep. From this the color varies to a pure white. 
Potato; a dry, granular, orange yellow growth, abundant and characteristic. 
Color varies toa white, and sometimes the growth is moist rather than dry. 
Bouillon; in two days a slight cloudiness is produced. In six days the 
liquid is very cloudy, but with no sediment. In four weeks very cloudy, 
‘with a yellow sediment. 
Milk; curdles at 36° in three days into a soft curd, with an amphoteric re- 
action. At 20° it curdles in the same way in ten days. ‘The curd is not 
subsequently digested, or only very slightly. When used for ripening cream in 
butter making, it produced very little flavor or aroma. 
No.159.* 4 Rare-) 
Morphology, a bacillus, size, .7@ by .gu. 
Gelatin plate; characteristic. A mounded, yellowish, spreading colony, 
which becomes sz centimeter in diameter, thin and almost invisible on the edge. 
Is irregular shaped and very yellow. 

* The variations of this species have Been previously described in the Cent. f. Bact. 
mp rar..1l:; Vi., Dp» 665. 
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