NON-PATHOGENIC BACILLI. 657 



this, may easily be mistaken for a micrococcus ; sometimes in pairs or in short 

 chains. 



Biological Characters. An aerobic, non-liquefying, non-motile bacillus. 

 Spore formation not observed. Grows slowly in the usual culture media at 

 the room temperature. Upon gelatin plates the deep colonies are yellowish 

 and punctiform ; under a low power they are seen to be opaque in the mid- 

 dle and have dentate margins; when they break through to the surface they 

 form small, prominent masses, and from these superficial colonies are de- 

 veloped which have a pale-greenish tint, a deeply dentate margin, and are 

 seen under the microscope to be finely granular In gelatin stick cultures 

 a very thin, smooth, shining layer is developed upon the surface; this has 

 an irregular and deeply dentate margin; the gelatin acquires a greenish 

 tint; no development occurs along the line of puncture. Upon the surface 

 of agar a smooth, shining layer with wrinkled margins is formed ; the agar 

 acquires a green tint. Upon potato a shining, flesh-colored layer extends 

 over a considerable portion of the surface. 



jrf?Sv, , ^ 



% % j^i 



FIG. 217. FIG. 218. 



FIG. 217. Bacillus scissus. X 1,000. (Frankland.) 

 FIG. 218. Bacillus scissus; superficial colony on gelatin plate, x 100. (Frankland.) 



334. BACILLUS NO. I. OF FULLES. 



Found in the soil. 



Morphology. Bacilli from 1 to 1.2 u long and 0.6 ja broad. 



Biological Characters. An aerobic, non-liquefying, motile bacillus. 

 Spore formation not observed. Upon gelatin plates forms spherical, finely 

 granular colonies ; under the microscope these have a yellowish-brown cen- 

 tre surrounded by a yellowish marginal zone ; later these differences in color 

 are not seen, and to the naked eye the colonies are bluish-white. In gelatin 

 stick cultures a thin layer forms upon the surface which is not characteris- 

 tic. In bouillon, at the room temperature, the liquid becomes densely 

 clouded and white flocculi are deposited at the bottom of the tube. Upon 

 potato a moist, dirty -yellow layer is developed. Not pathogenic for mice or 

 for guinea-pigs. 



335. BACILLUS NO. II. OF FULLES. 



Found in the soil. 



Morphology. Small bacilli with round ends; resemble cocci. 



Biological Characters. An aerobic, non-liquefying bacillus. Spore for- 

 mation not observed. Presents oscillatory movements only. Upon gelatin 

 plates somewhat elevated, round, grayish-white colonies are developed upon 

 the surface ; the deep colonies are small, yellowish in color, and under a low 

 power are seen to be finely granular, brownish-yellow, and with sharp con- 

 tours. The superficial colonies attain a diameter of two millimetres and 

 have a brownish-yellow color. In gelatin stick cultures the growth is at 



