458 



MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES. 



Fig. 21a. 



Fig. 216. 



invisible pellicle, with one or more dense wliitisli jiatclies in it; the liqiietied gelatin is densely 

 clouded, and may have a slight green tint; on the flow of the liquetiictiou there is a thick 

 floconlent deposit; there is only slight growtli in the line of Inoculation. 

 Acid gelatin. — Grows less vigorously aud with little or no liquefaction. 

 Aijar slanf. — Smooth, shining, whitish, semitranslncent strijte with 

 slightly irregular margins, not spreading widely; the agar acquires after a 

 time a faint green tint. 



Bouillon. — Clouded; a delicate pellicle may form on the surface: there 

 is asomewhat viscid sediment, and a greenish tint may appear in tlic liquid. 

 Potato. — Moist, viscid-looking, brownish growth, spreading rather 

 ■widely. 



Litmus milk. — Coagulation and separation of a cloudy serum after a 

 time. The milk is discolorized; there is a pink ring on the tube wall above 

 the level of the liquid, and the upper layer of the coagulated milk may be 

 pink also. The clot is firm. 



Sugar (/elatin in. deep stab. — Only faint development; no gas is formed. 

 Ronolic arid. — Decolorized; the reaction is neutral or alkaline 

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

 Relation to temperature. — Does not grow at S.")'^ to 3G° C. 

 Remarks. — A variety, 't, of this bacillus has been isolated from the same source. It is also a 

 polar flagellated bacillus and resembles the one above described in its morphology aud biological 

 characters, but shows the following main points of difference: In gelatin stab cultures it liquefies 

 much less rapidly than the variety a (see flg. 21 U), aud it requires a longer time to coagulate milk. 

 It also gives a less marked or doubtful indol reaction and seems to have a less active effect on 

 rosolic acid. In its colony growth in gelatin the same slowness in liquefaction is observed wlien 

 compared with the other organism. 



Bacillus Fainiiontensis. 



Isolated from the water of the Schuylkill Eiver. A medium-sized, generally short, motile 

 bacillus with rounded ends, often in pairs and sometimes in long forms and threads. It h.as a 

 terminal flagelluni; no spore formation observed. 



Colonies in gelatin. — By the second day the colonies on the surface appear as rounded, whitish, 

 semitranslucent disks, about 1 mm. or 2 mm. in diameter. Under a low magnifying power they 

 are seen to be rather dark at the center, with a greenish shimmer, but becoming thinner, 

 granular, and brownish toward the peiiphei'y, where they are quite thin and translucent. 

 The outline is smooth and sharply defined. Between the center and the periphery some 

 faint radiating lines may sometimes be observed, or near the margin an indistinct 

 mottled appearance. There is often a rounded, opaque, greenish nucleus at the center. 

 The deep colonies are rounded or oval, dense and granular, often showing a dark 

 greenish brown tint at the center, and have smooth, sharply defined outlines. By the 

 third day liquefaction may be well marked and the colonies are seen to be denser, to 

 have lost their sharply defined outlines, and to be surronnded by a zone of cloudy 

 liquefied gelatin. Under some circumstances the colony may now appear as a dirty 

 grayish membrane with folded or crimped margins lying in a saucer- shai)ed liquefaction. 

 The colonies of this bacillus in their early stages are nearly identical in appearance with 

 B. duplicatus. 



Gelatin stah. — Saucer-shai)ed liquefaction extending to tube wall in about three or 

 four days with slight growth in line of inoculation (fig. 22). Liquefaction gradually 

 extends downward, the liquefied gelatin being separated from the solid gelatin by a j^lT^ 

 horizontal plane on which collects a whitish sediment. The licpiefied gelatin is clouded, 

 and a thiu, easily detached, grayish membrane may be seen at the surface, more or less suni< in 

 the liquefied gelatin. 



Acid gelatin. — Liquefaction retarded. The reaction of the liquefied gelatin is alkaline. 



Agar slant. — Grayish white, shining, somewhat ek^vated, semitranslncent stripe, with rather 

 ■irregular and wavy, sharply defined margins. The growth shows some inequalities on the surface, 

 and does not spread widely. The agar acquii'cs a slight green tint after a time. 



