162 SPECIAL BACTERIOLOGY 



SPIRILLUM UNDULA. 



Found in putrid fluids, especially in infusions of straw. Thick, 

 strongly-motile spirilla, the flagella arranged in a bundle at one 

 pole (Lophotricha). (See Photomicrograph, Fig. 58.) 



Biological Characters. The optimum temperature appears to be 

 between 22 and 27 C. 



On Gelatine Plates it forms sharply defined, granular, greenish-yellow 

 colonies, while the medium appears to be slightly liquefied. 



In Gelatine Slab Cultures, on the upper portion of the puncture, a 

 veil-like clouding of the medium occurs, while round the opening of the 

 puncture a whitish growth with ragged tufted edges develops. 



On Agar Media the water of condensation is clouded, but no film is 

 formed. Kutscher distinguishes two forms Spirillum undula majus, 

 and Spirillum undula minus. 



BACILLUS DIPHTHERIA. 



This bacillus was first observed by Klebs (1883) in diphtheritic 

 false membranes. It was cultivated in pure cultures, and its patho- 

 genic properties demonstrated by Loffler in 1884. 



Microscopical Appearances. Somewhat plump rods of variable 

 sizes, 1 to 6 /A long, and 0'5 to 1 /* broad, either straight or slightly 

 curved, with rounded ends. Irregular forms are very common, and 

 indeed are characteristic of this bacillus. In the same culture and in 

 unfavourable media great differences in form and dimensions occur ; one 

 or both ends may appear swollen (see Photomicrograph, Plate IV., Fig. 

 19, in the centre of the field), or the central portion may be thicker 

 than the extremities, or the rod may consist of irregular, spherical, or 

 ovoid segments. The rods sometimes also lie in clusters alongside of 

 each other in a characteristic manner, like a bundle of faggots or a 

 spilled box of matches. They also occur in branched forms, but this 

 condition is comparatively rare. 



Spore Formation absent, but the cultures remain alive for five 

 months. 



Motility. Non-motile. 



Staining Reactions. The best results are obtained with methylene 

 blue, or a weak solution of carbol fuchsin ; gentian violet stains too 

 intensely, obscuring the structure of the organism. The reaction with 

 the Gram and Cladius methods is positive. Roux's double stain (see 

 Technique, p. 41) also stains the bacilli very well. Neisser has- recently 



