. Carnegie Institution of Washington publication. BROWN ROT OF SOLANACEAE. 195 day such milk was approximately Ridgway's indigo blue; after 3 months it was dark hya- cinth blue (pi. 23, fig. 7); but the fluid was neither viscid nor gelatinous. Litmus in milk is sometimes a little reduced (white) in the bottom of the tubes. The bacterial precipitate is white. In another set of tubes of litmus milk examined at the end of the seventh week the color was recorded as a clear intensely dark blue. All these milks were cream-free. Ljtmus-laetose-agar streaked with this organism becomes slowly a deeper
. Carnegie Institution of Washington publication. BROWN ROT OF SOLANACEAE. 195 day such milk was approximately Ridgway's indigo blue; after 3 months it was dark hya- cinth blue (pi. 23, fig. 7); but the fluid was neither viscid nor gelatinous. Litmus in milk is sometimes a little reduced (white) in the bottom of the tubes. The bacterial precipitate is white. In another set of tubes of litmus milk examined at the end of the seventh week the color was recorded as a clear intensely dark blue. All these milks were cream-free. Ljtmus-laetose-agar streaked with this organism becomes slowly a deeper blue. There is never any reddening, but sometimes the litmus is partially reduced and the agar finally browns. The behavior in cream-free litmus milk is like that of the culture figured on pi. 41. The streak of the District of Columbia organism on slant litmus-lactose-agar after 10 days at about 270 C. was white, wet-shining, and there was a copious whitish precipitate in the V; the upper half of the agar was blued very decidedly, in the lower half the litmus was reduced. The surface of the slant beyond the streak was iridescent. The agar was not then browned, but later (seventh. week) it was browned decidedly and the surface growth was a dirty brownish-white; the extreme upper part of the agar continued bluer than the check-tube, but in the lower part the formation of the alkali was masked by the brown stain and the reduction processes. The organism does not liquefy gelatin (experiments of 1895-96, repeated in 1904 and in 1905), at least not when made as described in vol. I of this monograph. The surface colonies in gelatin are small, circular, thin, thin-edged, smooth, white, wet-shining; the buried col- onies are globose, yellowish or brownish, and smooth, with well- defined margins. In stab-cultures (fig. 111) the upper part is best de- veloped, but growth was not rapid at 240 C. and ceased at io° C. The Virginia organism grown in gelatin- stabs for 7 days at 220 to 250 C,
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