THE CHAEACTEKISTICS OF BACTERIA 



43 



B. Cultural characters. 

 1. Gelatin stab. 

 I. NonliquefyiBg. 



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

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

 disjointed colonies (Fig. 21, B') ; ecMnulate, prickly 



C 



•A 



I 



I) 





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

 A, filiform ; B^ echinulate ; C, beaded ; D, effuse ; Ej arborescent 



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

 Uke extensions (Fig. 21, U) ; plumose, a feathery 

 growth; arborescent, beset with rootlike extensions 

 (Fig. 21, Ey 

 b. Surface growth. Same as for colonies on plate 

 cultures. 

 II. Liquefying. 



a. Type of liquefaction: crateriform, saucer-shaped 

 (Fig. 21, F') ; napiform, turnip-shaped (Fig. 21, G) ; 

 infundibuliform, funnel-shaped (Fig. 21, H^ ; saccate, 

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

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



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

 granular. 



2. Streak cultures (agar or potato). 



a. Growth: invisible, scanty, moderate, abundant, 

 h. Form: filiform, a narrow line (Fig. 22, A') ; ecMnulate, 

 growth along line of inoculation with toothed or 



