LABORATORY AND TEACHING METHODS 



627 



F. Optic Characters. — Transparent, vitreous, oleaginous, resinous, translucent, 

 porcelaneous, opalescent, nacreous, sebaceous, butyrous, cetaceous, opaque, creta- 

 ceous, dull, glistening, fluorescent, iridescent, color of colonies. 



G. Edges of Colonies. — Entire, undulate, repand, erose, lobulate, auriculate, 

 lacerate, fimbriate, ciliate. 



^iy 



Pig. 223. — Types of growth in stab cultures. A, Non-liquefyinp; i, Filiform 

 {Bacidiis coli); 2, beaded {Streptococcus pyogenes); 3, echinate {Bacterium acidi 

 lactici); 4, villous {Bacterium murisepticiim); 5, arborescent {Bacillus mycoides). 

 B, Gelatin liquefying. 6, Crateriform {Bacillus vulgare, 24 hr.) ; 7, napiform {Bacillus 

 sublilis, 48 hr.); 8, infundibuliform {Bacillus prodigiosus) ; 9, saccate {Microspira 

 Finkleri); 10, stratiform {Pseudomonas flavescens). {From McFarland after Frost in 

 Schneider, Albert: Bacteriological Methods in Food and Drug Laboratories, 1915: 87.) 



TYPES OF STAB CULTURES 



A. Surf ace Growth. — Filiform, beaded, echinate villous, arborescent. 



B. Character of Liquefied Gelatin. — Pellicle on surface, uniformly turbid, granular, 

 mainly clear but containing flocculi, deposit at apex of liquefied portion, production 

 of gas bubbles. 



C. Area of Liquefaction (if present). — Crateriform, saccate, infundibuliform, 

 napiform, fusiform, stratiform (Fig. 223). 



