CHAPTER 13 



DESCRIPTION OF THE METHODS USED IN THE SYSTEMATIC 

 EXAMINATION OF BACTERIA, AND A GLOSSARY OF THE 

 TERMS EMPLOYED 



We have already dealt in Chapter 12 with the methods of isolating pure cultures 

 of bacteria, and with the various criteria that are employed in their identification. 

 In the present chapter we describe a routine which may be used in examining 

 the various morphological, cultural, and biochemical properties of bacteria, and 

 define the terms which we shall employ in the description of these properties. 

 Morphological Appearance of Bacteria. — The chief points to be noted are the 



following : 

 Shape. — Spheres, short rods, long rods, filaments, commas, or spirals. 

 ^xt5.— Straight or curved. 

 Size. — Length and breadth. 

 Sides. — Parallel, bulging, concave, or irregular. 

 Ends. — Rounded, truncate, concave, or pointed. 

 Arrangement. — Singly, in pairs, in chains, in fours, in groups, in grape-like clusters, 



in cubical packets, in bundles, or in Chinese letters. 

 Irregular Forms. — Variations in shape and size ; club, filamentous, branched, 



navicular, citron, fusiform, giant swollen forms and shadow forms. 

 Motility. — Motile or non-motile. 



Flagella. — Monotrichate, amphitrichate, lophotrichate, peritrichate (Fig. 13, p. 31). 

 Endospores. — Spherical, oval, or ellipsoidal ; equatorial, subterminal, or terminal ; 



single or multiple ; causing bulging of bacillus or not (Fig. 6, p. 24). 

 Capsules. — Present or absent. 

 Staining. — Even, irregular, unipolar, bipolar, beaded, barred ; and variations in 



depth between different organisms. Presence of metachromatic granules ; 



reaction to Gram and to Ziehl-Neelsen stains. 



Surface Colonies on Solid Media. 



Shape. — Circular, irregular, radiate, rhizoid. 



Size. — In millimetres. 



Elevation. — Efiuse, raised, low convex, convex or dome-shaped, umbonate, um- 



bilicate ; with or without bevelled margin. 

 Structure. — Amorphous ; fine, medium, or coarsely granular ; filamentous, curled. 

 Surface. — Smooth ; contoured, beaten-copper ; rough ; fine, medium, or coarsely 



granular ; ringed ; papillate ; dull or glistening. 

 Edge. — Entire, undulate, lobate, crenated, erose, fimbriate, curled, effuse. 



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