LABORATORY AND TEACHING METHODS 



627 



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

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

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



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

 lacerate, fimbriate, ciliate. 



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i 



X 



vL/ 



vjy viy 



Fig. 223. — Types of growth in stab cultures. A, Non-liquefying, i. Filiform 

 (BaciUus colt); 2, beaded {Streptococcus pyogenes); 3, echinate (Bacterium acidi 

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

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

 subtilis, 48 hr.); 8, infundibuliform (Bacillus prodigiosus) ; 9. saccate (Microspira 

 Finkleri); 10, stratiform (Pseudomonas Jlavescens). (From McFarland after Frost in 

 Schneider, Albert: Bacteriological Methods in Food and Drug Laboratories, 191S: 87.) 



TYPES OF STAB CULTURES 



A. Surface Growth. — Filiform, beaded, echinate villous, arborescent. 



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

 mainly dear but contaiiiing 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). 



