THE CHARACTERISTICS OF BACTERIA 



43 



B. Cultural characters. 

 1. Gelatin stab. 

 I. Nonliquefying. 



a. Line of puncture : filiform, uniform needle-shaped 

 growth (Fig. 21, A) ; beaded, succession of small, 

 disjointed colonies (Fig. 21, B) ; echinulate, prickly 



FIG. 22. Types of growth of bacteria on streak cultures 

 A, filiform ; />, echinulate ; C, beaded ; I), effuse ; E, arborescent 



(Fig. 21, C); villous, beset with unbranched hair- 

 like extensions (Fig. 21, 1)} ; plumose, a feathery 

 growth ; arborescent, beset with rootlike extensions 

 (Fig. 21, E). 

 b. Surface growth. Same as for colonies on plate 



cultures. 

 II. Liquefying. 



a. Type of liquefaction : crateriform, saucer-shaped 

 (Fig. 21, 7 y ") ; napiform, turnip-shaped (Fig. 21, (V); 

 infundibuliform, funnel-shaped (Fig. 21, //); saccate, 

 sac-shaped (Fig. 21, /) ; stratiform, the liquefaction 

 descending in a horizontal plane (Fig. 21, </"). 



b. Character of the fluid: clear, cloudy, flocculent, 

 granular. 



2. Streak cultures (agar or potato). 



. Growth: invisible, scanty, moderate, abundant. 

 I. Form: filiform, a narrow line (Fig. 22, .-/); echinulate, 

 growth along line of inoculation with toothed or 



