380 IMPORTANT VARIETIES OF FISSION-FUNGI. 



gelatin plates show the deep colonies as yellowish, round, finely 

 granular, and sharply outlined; the superficial are similar, but more 

 spreading, thin films. The gelatin stab culture presents a delicate 

 growth in the stab, and yellowish, abundant surface growth, with 

 gradual liquefaction and formation of an air space. No growth 

 upon potato. Nutrient fluid rapidly becomes turbid with a thick 

 pellicle. As Kutscher also remarks, Beijerinck's descriptions of three 



Fig. 19. Spir. tenue Ehr., after Migula. 



forms of Sp. tenue (C. B. L. I, 1) are not sufficient for identification. 

 Bonhoff found one form deviating somewhat from Kutscher's descrip- 

 tion ; for example, with only two flagella on each side. 



Spirillum undula. Ehrenberg, emend. Cohn and 

 Kutscher. 



Relatively large threads; usually | to 1, rarely 1J to 3 turns; 

 height and diameter of each turn, 4-5 //. After longer cultivation 

 there are often scarcely any except straight forms. With terminal 

 bunches of flagella, three to fifteen in number. In gelatin plates there 

 occurs only in the depth a slow growth of sharply outlined, finely 

 granular colonies, beneath which the gelatin sinks a little. In the 

 stab culture development takes place in the upper two-thirds of the 

 stab; the growth on the surface of the gelatin is thin, whitish, slightly 

 lobulated, and after ten days sinks slowly into a depression. Grows 

 on potato. Nutrient fluids uniformly cloudy, without pellicle. 



Recently Zettnow and Kutscher have differentiated from this Spir. 

 undula minus also a Spir. undula majus, which is about one-third 

 larger and grows well on meat-infusion gelatin and agar (C. B. XVIII, 

 614; XIX, 393). 



Spirillum volutans. Ehrenberg, emend. Cohn and 

 Kutscher. 



Not only the largest spirillum, but one of the largest varieties of 

 bacteria. The threads are about 2-3 fi thick and spirally wound, the 

 height of a turn being fi.6 //, length 13.2 //; usually there are 2| to 3J 

 turns. In cultures the forms are smaller, similar to the Spir. rubrum. 

 According to Cohn, they have one large flagellum at each end; accord- 

 ing to A. Fischer and Kutscher, a terminal tuft of three to eight long 

 flagella, which are often plaited together'. The colonies in gelatin 

 plates at first resemble those of Bact. coli; later the gelatin sinks in, 

 and the peripheral parts of the colonies break up. Agar plates are 



