MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES. 39 



The center is brown in color, and appears broken and fissured in every direction. Next is a zone 

 much darker, but also brown in color, and fissured even more than the center. It begins quite 

 abruptly and Cades toward the edge gradually until it becomes gray. The gelatin is slowly 

 softened rather than liquefied, and the colonies attain a diameter of 2 to 3 mm. Around the 

 white central portion can be seeu a faint halo, which under the microscope shows the same fissured 

 character as the body of the colony, but is without color. As the growth gets older the zones 

 become less distinctly defined, while the fissures get plainer. 



Agarslant. — Very thin layer,3to4 mm. wide, with nidistiuct edges, which finally look so much 

 like agar that it is impossible to tell just where the growth begins. It is greenish white and 

 translucent. 



Gelatin stab. — Slight growth down puncture, and on the surface a button forms. After eight 

 or nine days this button has sunk into the gelatin, but no liquid can be detected, evaporation 

 going on as rapidly as liquefaction. At some distance below the surface may be 

 seen globular outgrowths ranged along the stab. They are white and indistiuct. 

 After two weeks the cup of liquefaction is only <> mm. deep. 



Gelatin slant. — Band 4 mm. wide forms, which is not elevated, and has even 

 edges. Surface of the growth is iridescent, and pale green by transmitted light. 

 From the lower surface of growth rounded projections pierce the gelatin. The 

 gelatin liquefies slowly and the growth slips to the bottom. 



Potato. — Growth is scarcely visible until third day, though a bluish discolora- 

 tion is seen along needle mark. It becomes abundant, of yellowish color, smooth, 

 moist, and shining, resembling a thiu layer of honey. 



Bouillon.— Slight cloudiness at first. Growth settles to bottom later, leaving 

 liquid tolerably clear. 



Rosolic acid. — Color is almost entirely lost, by the third day. Gel stab 



Litmus milk. — Becomes bluer without coagulation. After two weeks it becomes translucent, 

 and is a beautiful violet color by transmitted light. 



Sugar gelatin, deep stab. — Growth quite deep and on surface, same as plain. No gas production. 



Indol. — Reaction negative. 



Relation to temperature. — Grows more rapidly at 35° to 3G° C. 



Bacillus Arborescens Non liquefac'iens. 



(Fig. 38, l'l. Ill, ami Figs. 39 audio. PI IV ) 



Isolated from made earth at depth of 2 feet. 



Character. — Strict aerobe. No growth in au atmosphere of hydrogen. 



Morphology. — Straight, slender rods, with rounded ends, from seveu to thirteen times as long 

 as brond. Occurs singly and in chains of several elements. 



Spores not demonstrated. 



Motility.— Rods turn almost end for end, and back again. No progression noticed. 



Flagella not demonstrated. 



Colonies on gelatin plates. — Visible at end of forty-eight hours, as bluish, indistinct, cloudy 

 dots, easily overlooked. The deep colonies can not be distinguished from those on surface. They 

 resemble the colonies of the Ramosus, but are less distinct, smaller and not so white, nor do they 

 grow so rapidly. Each colony consists of an axial trunk, both ends of which split up into 

 uumberless fine lines, somewhat interlaced, but on the whole radially disposed. These terminal 

 branches are six to seven times as long as the trunk itself. In some colonies the trunk splits into 

 several large branches, each of which gives rise to many fiueoues, the whole giving a star shaped 

 figure. Others are made up of several sticks loosely laid together, each one of which splits up 

 into tine branches at both ends; while others again are like the branch of a tree, one end breaking 

 into smaller branches, which then break up into finer lines, while the other end is larger, and 

 breaks up directly into the fine brush like filaments. After four days the colonies become more 

 plainly visible, like bluish clouds. Under the low power (80 diameters) the tine terminal hues 



