30 MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES. 



Gelatin slant. — Resembles the growth of the typhoid bacillus very closely. A dry, white line, 

 thin and with iridescent gleam, and later cracks across the surface transverse to the long axis. 



Gelatin -stub. — Growth is confined to the surface mostly for tlie first three or four days, 

 forming a button like a drop of milk. By the fourth day there is good development to the bottom 

 of the puncture, being in separate colonies low down, as minute white spheres. 

 The growth on the surface attains a diameter of 4 mm. by the eighth day, and is 

 elevated 1 mm., witli a slight central depression. It is porcelain white and has 

 even edges. The gelatin becomes opaque around it, but no growth can be detected 

 with the needle. The button later becomes cream colored. There is no liquefaction. 

 Potato. — At the end of twenty-four hours a line of moisture is seen along the 

 ueedle mark. By the next day it has spread widely in a thin whitish layer. It 

 iucreases in thickness, and has a curdled appearance. At the end of two weeks it 

 becomes thick and pasty looking, and the color of putty. 



Bouillon. — Becomes diffusely clouded by the third day, and later a dirty-white 

 Gel. stab. deposit is seen on the bottom. 

 Bosolic mid. — Becomes lighter by the third day, and the color is almost entirely discharged 

 at the end of a week. Reaction alkaline. 



Litmus milk. — The color becomes a pure blue in three days and then grows darker, until at 

 the end of three weeks it is slate colored. There is no change apparently in the milk itself. A 

 white deposit collects at the bottom. 



Sugar gelatin, deep stab. — Growth in separate colonics deep down, with button on the surface. 

 There is no gas produced. 



Indol. — Reaction negative. 



Relation to temperature. — More rapid at 35° to 36° C. 



Note. — This bacillus resembles the Geminus minor very closely in many ways. The chief 

 points of diagnosis are the discharging of the color of rosolic acid, while the former changes it 

 to cherry red, and the formation of single colonies in the bottom of gelatin stab cultures. 



Bacillus Cinctus. 



(Figs. 24, 25, and 26, PI. HI.) 



Found at the depth of i feet in made soil, which had been paved over for several years. 



Character. — Very slight growth in an atmosphere of hydrogen. 



Morphology. — Straight rods which vary considerably in size. Involution forms are found in 

 eighteen to twenty hours in agar cultures kept in the incubator. It occurs singly mostly, but 

 chains of several elements are found also, the line of division not being well marked. Each rod 

 has from one to three deeply stained dots in it, placed irregularly, though a majority are at, or 

 near, the poles. These do not seem to have anything to do with spore formation, as they are seen 

 in spore-bearing rods. 



Spores are formed in three days at room temperature. They are large ovals, and distend the 

 walls of the cells. Formed near the ends. 



Motility. — It is actively and progressively motile. 



Flagella not demonstrated. 



Colonies on gelatin plates. — Colonies seen in twenty to twenty-four hours as indistinct trans- 

 lucent points, which, under a low power, are yellowish, granular disks, with even margins. Growth 

 is slow, and at the end of seventy hours the deep colonies are still punctiform, while those on the 

 surface are one-half of a millimeter in diameter. The latter are greenish white, with irregular 

 margins, x 80. The surface colonies show a nucleus, eccentrically placed, around which is a 

 zone, yellowish in color, which appears granular at first. A close study shows fine lines so closely 

 laid as to produce this appearance. Outside of this is a zone of gray, which is irregularly veined, 

 and has very irregular margins. There is but little change from day to day. At the end of eight 

 days the surface colonies are only 1 mm. in diameter, greenish white, round, and elevated, with 

 even margins. The deep are about one-sixth of a millimeter in diameter, and grayish, x 80. 

 Deep are a bright yellow with reddish tinge, fading gradually to a grayish color at the margins, 



