444 



MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES. 



diameter of 7 mm. or more, and may ahow one or two ciouceiitric, hazy, yellowisli rings formed of 

 yellowish flocculi. 



Gelatin stab. — Liciuefactiou is saucer or cup form, with only faint development along 

 the line of inoculation (fig. 3). The li(]uefled gelatin is clouded, and an abundant yellow 

 llocculent deposit is seen at the bottom; there may be a delicate, somewhat iridescent 

 pellicle on the surface; the liquefied gelatin has an alkaline reaction. 

 Acid gelatin. — Good growth; no growth in line of inoculation. 



Afiar slant. — "Warm, yellow, seniitranslueent stripe, with wavy margins and a 

 smooth shining surface. 



Bouillon. — Clouded, and tlocculi in suspension. A yellow pellicle forms on the 

 surface, and there is an abundant, thick, membranous sediment, of a yellow color; the 

 reaction is alkaline. 



Potato. — Thin, moist, spreading, brown-yellow colored growth. 



Litmus milk. — Coagulated and decolorized; clot rather firm and serum clouded; 



\ / pink ring on tube wall; yellowish deposit at bottom of tube; reaction is acid. 



Rosolic acid. — Color much deepened; reaction is alkaline. 

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

 Relation to temperature. — Does not grow at 3o^ to 30° C. 



V^ 



Fig. 3. 



Bacillus caudatus. 



Isolated from the water of the Schuylkill River. Not frequent in occurrence. A rather 

 small, slender, nonmotile bacillus with conical ends, occurring often in pairs and in longer forms, 

 sometimes thread-like, which may show irregular segmentation; no spore formation observed. 



Colonics in (jelatin. — About the third or fourth day the surface colonies are rounded, yellow, 

 seniitranslueent disks, with smooth or slightly wavy, sharjjly defined outlines, and a diameter (»t 

 1 mm. to 2 mm. (See PI. I, fig. 7.) Under a low power they are translucent and of a light yellow color, 

 becoudng colorless at the margin, which is sharply defined and smooth or slightly wavy. At the 

 center a small nucleus may be observed, and from this delicate lines radiate toward the periphery. 

 Sometimes various delicate indistinct markings may be made out in the colony in addition to these 

 radiating lines. The deep colonies under the low power are seen to be yellow in color, irregularly 

 rounded, and sharply defined in outline. Tiiey are seniitranslueent, faintly granular, and may 

 show faint radiating lines. Sometimes deep colonies may be seen which have short hair-like 

 lirocesses extending into the gelatin in an irregular manner. (See PI. I, fig. 8.) In stiff gelatin 

 these hair-like processes may be quite numerous and long, giving the colony a hazy 

 appearance to the naked eye and extending into the gelatin on all sides from the 

 colony as a center. In the course of a few days the colonies on the surface sink 

 somewhat in the gelatin, and some may become surrounded by a zone of liquefied 

 gelatin in which what appear to be yellow flocculi may be seen. Under the low power 

 the typical and characteristic li(]uefying colony is seen to consist of a brown-yellow, 

 somewhat refracting, coarsely granular central portion, surrounded by a broad zone 

 consisting of coiled and twisted, more or less yellowish and translucent bands or cords, 

 which lie in the li(juened gelatin and give the impression of yellowish flocculi to the 

 naked eye, as above noted. This aiipearance seems to be brought about through a 

 radial splitting of the surface exi)ansion and a lengthening and twisting of the process 

 thus formed. All grades of transition between this typical condition and the original 

 colony are quite commonly to be observed. Sometimes in colonies, slightly sunken in 

 the gelatin, short hair-like tufts maybe observed springing from the margin at different 

 jioints and projecting into the gelatin in an irregular manner; li(iuefactiou is slow. 



Gelatin stab. — Liquefaction is cup shape or deep saucer form, sometimes constricted 

 at the top and inclosing an air space. (See fig. 4.) The liquefied gelatin is densely clouded and 

 contains a thick, yellow, floccnlent material, while a yellow scum may be observed on the surface. 

 Beneath the liquelaction there is a yellow haziness in the gelatin, and this continues down tlie line 

 of inoculation, gradually fading out. In some cases this haziness may be observed to take the form 



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