NON-PATHOGENIC BACILLI. GG9 



softened, these colonies are seen to consist of a network of interlaced fila- 

 ments ; at the centre a thicker portion is often seen in the cloud-like colonies 

 of interlaced threads; liquefaction progresses rapidly, the colonies become 

 confluent, and soon the plate is destroyed. In gelatin stick cultures the 

 gelatin is liquefied upon the surface, but liquefaction does not progress rap- 

 idly ; the liquefied gelatin is clouded, and a yellowish deposit accumulates 

 at the bottom of the liquefied gelatin ; along the line of puncture, almost to 

 the surface, no growth is seen, but around it a row of flat, horizontal rings 

 are developed, the diameter of which increases from above downward; the 

 lower end of the line of puncture is uniformly clouded ; the rings described 

 are made up of delicate, cloud-like masses ; the culture somewhat resembles 

 that of the bacillus of mouse septicaemia; liquefaction progresses slowly, but 

 finally the entire amount of gelatin is liquefied. Upon the surface of agar a 

 thin, opalescent, bluish-white layer is formed, the fringed margins of which 

 show a violet fluorescence. In bouillon a diffuse cloudiness is developed, 

 and a dirty- white deposit collects at the bottom of the tube, while a very 

 thin film collects upon the surface ; this falls to the bottom, when the tube is 

 shaken. Upon potato the growth is almost invisible and of a very faint yel- 

 low color; it extends, however, over a great portion of the surface. 



356. BACILLUS PESTIPER (Frankland). 



Found in the air. 



Morphology. Bacilli with round ends, 2.3// long and 1 /* broad; often 

 grow out into filaments. 



Biological Characters. An aerobic, liquefying, motile bacillus. Spore 

 formation not observed. Grows slowly at the room temperature. Upon 

 gelatin plates forms colonies resembling those of Bacillus vermicularis, but 

 the deep colonies are more regular and the superficial colonies have a smooth 

 centre. Upon the surface of agar a shining, transparent layer with dentate 

 margins. Upon potato a thick, irregular, flesh-colored layer. 



357. BACILLUS FILIFORMIS (Tils). 



Found in water. 



Morphology. Bacilli with round ends, 4 jn long and 1 u broad ; usually 

 united in chains, which may consist of as many as ten segments which are 

 indistinctly separated from each other. 



Biological Characters. An aerobic, liquefying bacillus. Exhibits os- 

 cillatory movements only. Forms, in potato cultures, large oval spores. 

 Upon gelatin plates grayish-white colonies are developed which have a 

 marbled structure; under a low power the deep colonies are seen to be finely 

 granular and irregular in outline ; the superficial colonies have a dentate 

 margin, which is composed of many bundles of bacilli closely crowded to- 

 gether; the centre is somewhat rough, elevated, and granular; the colonies 

 are colorless at the margin, but have a yellowish color at the (^nti-e; at the 

 end of eight to ten days liquefaction commences and the colonies sink slowly 

 beneath the surface. In gelatin stick cultures a moist layer with deeply 

 dentate margins forms around the point of puncture; the gelatin is slowly 

 liquefied and thick, flocculent masses of bacilli accumulate at the bottom. 

 In bouillon growth occurs chiefly upon the surface in the form of a firm my- 

 coderma. Upon the surface of agar a white layer is developed like that 

 upon gelatin. Upon potato a thick, slimy, dirty- white layer, which later 

 becomes dry and acquires a gray or brownish color. In milk coagulation 

 occurs at the end of tliirty-six hours, and an odor of putrefaction is perceived. 



358. BACILLUS DEVORANS (Zimmermann). 



Found in well water. 



Morphology. Bacilli with round ends, from 0.09 to 1.2 /* long and about 

 0.74 // thick; solitarv, in pairs, or occasionally in short chains. 

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