r^ 



MEMOIES OF THE NATIONAL ACADEMY OF SCIENCES. 31 



showing several zones or concentric circles. The center is indistinctly veined and granular, the 

 edges smooth and clear cut. The cause of the zones is not apparent, as there is no abrupt change 

 in color or density. The surface colonies still showa nucleus, surrounded by a reddish-yellow zone, 

 which has smooth edges and fades evenly from center to margin. It is finely veined and some- 

 times mottled. Some colonies have a striking resemblance to the shell of an oyster. When 

 there are very few on the plate, grotesque forms are produced after a time, ferny outgrowths 

 going from the margins. These spread in most irregular shapes, later inclosing islands of gelatin, 

 by the projections meeting each other. They attain a diameter of -I mm. 



Agar slant. — A thin, glistening, pale green layer forms along the line of inoculation which 

 has spread to the tube wall for the lower half by the second day. It increases somewhat, but is 

 always thin and translucent, with smooth surface. The agar becomes a faint yellow. 



Gelatin slant. — A white band is formed, 1 mm. wide, with rather uneven edges. After a time 

 it cracks across the long axis, and the gelatin seems somewhat softened at the end of five weeks, 

 but no liquefaction occurs. 



Gelatin stab. — Growth occurs along puncture, and a white layer forms on the surface, which 

 has very irregular leafy margins, and attains a diameter of 2 mm. No liquefaction is 

 caused. 

 S \ Potato. — Only a widespread moisture is seen at first, which by the 



third day has become like a thin layer of honey in appearance. It is 

 moist and shining and very thin. After a time it becomes slightly 

 \ / darker. 



\^__^ / Bouillon. — Diffuse cloudiness in twenty-four hours. The growth 



surface growth. settles to bottom after two weeks, leaving the liquid tolerably clear. 



ii.1. stab. . . . . , _ 



The bouillon acquires a faint greenish color. 



Rosolic acid. — Becomes very slightly darker after three or four days. 



Litmus milk. — Becomes darker blue on third day, but soon begins to lose its cki.stab. 

 color. There is no coagulation. Beaction alkaline. 



Sugar gelatin, deep stab. — Growth some distance down puncture, and on the surface similar to 

 plain gelatin. No gas produced. 



Indol. — Beaction negative. 



Relation to temperature. — More rapid and abundant at 35° to 36° ('. 



Xote. — In the Zeitschrift fur Hygiene, Vol. IV, page 2">, is an article on the " Xerosis Bacillus 

 and its spore formation.'' The drawings correspond exactly with the organism just described, but 

 the description, as far as it goes, is different. 



Bacillus Yacuolatis. 



(Fig. 27. PI. III.) 



Found at the depth of 7 feet in made soil, which had been paved for several years. 



Character. — Strict aerobe; no development in an atmosphere of hydrogen. 



Morphology. — Eesembles the Klebs-Loffler bacillus very closely in its manner of staining, 

 though it is much longer and more regular in shape. The rods are single, straight, and have 

 rounded ends. Botato cultures form chains of several elements. The transverse bands which 

 remain unstained give the rods a ringed appearance. It is best seen when the culture is about a 

 week old. 



Spores are large and oval, and may be seen at the end of twenty-four hours. 



Motility. — -Shows movements which are not very active. 



Flagella not demonstrated. 



Colonies on gelatin plates. — Colonies appear in thirty-six to forty hours. Those on the surface 

 grow rapidly, and in forty eight hours have become one half of a millimeter in diameter. They 

 have a circular outline and are whitish, looking like drops of thin milk. By transmitted light they 

 are bluish. The deep colonies are punctiform. x 80 . Deep are yellowish, finely granular disks, 

 with even edges. Surface are yellowish in color, have an irregular, though clean-cut outline, and 

 are granular or mottled in appearance. A nucleus, usually eccentric, is present in most of them. 



