NOT DESCRIBED IX PREVIOUS SECTIONS. 529 



Upon agar a grayish-white layer is developed. Upon potato a thick, yel- 

 lowish layer is formed ; this is viscid and contains numerous gas bubbles. 

 In milk coagulation is produced at the end of twenty-four hours, and an 

 abundance of gas is given off. In bouillon containing milk sugar it multi- 

 plies abundantly and a large quantity of gas is liberated. Grows best at a 

 temperature of 30' to 35 C. Thermal death-point 60 C. fifteen minutes' 

 exposure. 



BACILLUS b. 



Morphology. Resembles bacillus a ; bacilli from 1 to 2 // long and about 

 1 n thick. 



Biological Characters. Anaerobic and facultative anaerobic, liquefy- 

 ing, motile bacillus. Is differentiated from a by the fact that it causes lique- 

 faction of nutrient gelatin after an interval of several weeks, and by the fact 

 that the young colonies upon gelatin plates are quite viscid. Spore forma- 

 tion not observed. Thermal death-point 80 C. five minutes' exposure. 

 An abundance of gas is given off from cultures containing milk sugar. 



BACILLUS C. 



Morphology. Short bacilli ; often oval or even spherical in form ; about 

 1 n long. 



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

 formation not observed. Upon gelatin plates colonies are developed which 

 resemble those of bacillus a, but are more closely granular ; the colonies 

 are very adherent and difficult to remove from the culture medium. Upon 

 agar a viscous, white layer is developed. Upon potato the growth is of a 

 yellowish- white color and similar so that of a and b, with gas bubbles ; it is 

 very adherent. In liquid media the growth of this bacillus causes the cul- 

 ture liquid to become extremely viscous and almost gelatinous in consistence. 

 In milk coagulation occurs at the end of sixty hours at 37 C., and the milk 

 then loses its viscosity. 



181. BACILLUS AEROGENES MENINGITIDIS (Centanni). 



Found by Centanni (1893) in two fatal cases of meningitis. 



Morphology. Bacilli from 2 to2.5/^ long and // thick, with rounded 

 extremities ; solitary, in pairs or in short chains. 



Biological Characters. An aerobic and facultative anaerobic, motile, 

 liquefying bacillus. Spore formation not demonstrated. Grows in the 

 usual culture media at the room temperature. In gelatin stick cultures len- 

 ticular gas bubbles are developed ; gas bubbles are also developed in profu- 

 sion in the abundant growth upon the surface of cooked potato. 



Pathogenic for rabbits. 



182. PNEUMO-BACILLUS SEPTicus (Galtier). 



Found by Galtier in the pulmonary exudate, etc., in calves suffering 

 from the infectious pleuro-pneumonia, or pneumo-enteritis, to which it gives 

 rise. 



Morphology. Spherical, oval, or rod-shaped bacteria, usually in pairs, 

 sometimes in short chains. The rods are sometimes three or four times as 

 long as broad, with round ends. Stains with the usual aniline colors, but 

 not by Gram's method. 



Biological Characters. A motile, aerobic, and facultative anaerobic, 



non-liquefying bacillus. (It does not liquefy gelatin under ordinary con- 



ditions, but when recently prepared and containing less than the usual 



amount of gelatin, liquefaction may occur.) Grows rapidly in the usual 



37 



