452 MEMOIHS OF THE NATIONAL ACADEMY OP SCIENCES. 



Colonies in gelatin. — On the second day the surface colonies have formed saucer-shaped liqiae- 

 factions, which aie cloudy and contain more or less whitish material in clnmiis; their outlines are 

 sharply detined and circular. Under a low magnifying power the li(iuetied gelatin is seen to be 

 ])ermeated by a more or less dense network of fibrils, and to be limited at the periphery by a fringe 

 of short, hair like processes which radiate into the uonliqueticd gelatin. (See PI. I, fig. 11.) In 

 some cases a coarsely granulated appearance of the liquefied gelatin maybe observed and motion 

 of a circulating character may be seen in it. The deep colonies under the low power appear as 

 dense, opaque, rounded bodies, sometimes having a greeuish shimmer, from which numerous 

 hair-like i)rocesses, some of which may be quite long, extend into the gelatin in a somewhat 

 irregular manner; liquefaction progresses rapidly. 



Gelatin stab. — Liquefaction quickly spreads to the tube wall at the surface and more slowly 

 extends along the line of inoculatiou ; liquefaction extends downward and laterally from the 

 line of inoculation until all the gelatin is li([uefied. (See fig. 12.) A thick, wrinkled, 

 white mycoderm forms on the surface; immediately beneath this the licpiefied gelatin 

 is clear, while thick, flocculent, whitish masses collect in the lower portions of the 

 liquefaction. The reaction of the liquefied gelatin is alkaline. 



Acid gelatin. — Grows well; no liquefaction along line of inoculation; liquefaction 

 is retarded and proceeds from above downward with a level flow. 



Agar slant. — Graj', white frosted, or velvety felt like membranous layer with 

 somewhat furred margins; in older cultures it becomes denser, smooth and shining, 

 and the margins more sharply defined and wavy, while the agar acquires a slight 

 smoky brown-greeu color; a few wrinkles may sometimes be observed in the growth. 



Bouillon. — Clouded at first; later a thick, white, friable mycoderm, which sinks to 

 the bottom when the tube is shaken, forms on the surface. 



Potato. — White, moist, velvety, rather thick, and widely spreading layer; later 

 V I y it becomes shining, and may have a slimy appearance. 



j,j^ J, Litmus milk. — Coagulated and decolorized; the coagulum is viscid or jelly-like, and 



the serum is dark colored and clouded with fiocculi and irregular clumps in suspension; 

 there is a bluish ring on the tube wall above the level of the liquid, and the reaction is alkaline; 

 the casein seems to be slowly dissolved. 



Siigar gelatin in deep stab. — Good growth with liquefaction; no gas is foi-med. 

 Rosolic acid. — No growth. 



Indol production. — Faint reaction; does not produce nitrites. 

 Relation to iemper((ture. — Grows well at room tenqjcrature and at 35° to 36° C. 

 Remarhs. — Tils found this organism among the many species described by him in his report 

 on the water supply of Freiburg. (Zeitsch. fiir Hygiene, Bd. IX, p. 315, 1890.) 



Bacillus detrudens. 



Isolated from the Schuylkill water. Seems to be a common contaminating organism, 

 especially in potato cultures. A medium-sized motile bacillus, with blunt ends, about two or 

 three times as long as broad, occurring singly, in pairs, and in long forms. It 

 has numerous flagella. Forms rather small, oval spores, about as broad as the 

 bacillus, usually situated nearer one end of the rod. (See iig. 13.) 



Colonies in gelatin. — On the second or third day the surface colonies appear 

 as whitish, rounded, semitranslneent disks, with smooth, sharply defined outlines, j.,q jg 



1 mm. to 2 mm. in diameter. Under a low i)Ower the colony is seen to be brownish 

 and granular, growing more translucent toward the edge, which is smooth and sharply defined. 

 Toward the center the colony is nnich darker and may have a greenish shimmer, and a central 

 nucleus may be observed. Between the center and the perijihery scattered coarser granules or 

 faint lines may sometimes be seen. The deep colonies are generally rounded, oval, or slightly 

 irregular in outline. (PI. I, figs. 11 and 15; PI. II, fig. 3.) They are rather dense, brownish in 

 tint, and highly granular, with .sharply detined outlines. Sometimes, apparently in soft gelatin, 

 the deep colonies nuvy form very irregular figures by the outgrowth of daughter colonies as 







