100 SUMMARY OF CURRENT RESEARCHES RELATING TO 



beiug gradations from a semicircle down to a straight line. The bacilli 

 are aggregated into groups, and do not form continuous threads. About 

 individual rods an unstained periphery is evident, but the possession of 

 a capsule is not conclusively demonstrable. Pure cultivations were 

 obtained by breeding, first in bouillon, then in gelatin, and afterwards 

 isolating on gelatin -plates. On the plates the colouies became visible 

 on the third day, and by the fifth attained a diameter of 0*3 mm.; by 

 the next day their size was noarly doubled. In tube cultivations the 

 colonies spread along the inoculation track, there being no surface 

 development and no liquefaction of the medium. In agar the develop- 

 ment was similar but more luxuriant. On potato no growth occurred. 

 The morphological variations are manifold and complicated, although 

 the fundamental form is a bent rod. In bouillon it almost always occurs 

 as single rods, the ends of which stain deeply, the central part remaining 

 uncoloured. Such forms therefore simulate diplococci, and raise a 

 suspicion of spore-formation. Cultivated in agar or gelatin, single 

 rods occur, but most frequently the individual elements are united to 

 form chains, which are most perfect in the agar. Staining is easily 

 effected with gentian violet and decoloration by Gram's iodine. Weak 

 spirit (1:3) dissolves out the dye from the stained medium, and leaves 

 the bacilli still coloured. The formation of spores could not be proved. 

 In hanging drops only Brownian movements were perceived. The 

 author has repeatedly made pure cultivations of the vibrio from his own 

 nasal mucus, but declines to give a definite opinion as to its general 

 frequency. Subcutaneous inoculations produced no effect on mice. 



Two kinds of Vibrios found in decomposing Hay Infusion.* — Dr. 

 E. Weibel obtained from rotting hay infusion two kinds of vibrio by 

 means of the attenuation method. A needleful of the fluid was diluted 

 with so much sterilized water that in each drop only a very few germs 

 were included ; from this a series of test-tubes filled with sterilized hay 

 infusion were inoculated. In two tubes vibrios predominated. From 

 these gelatin-plate cultivations were made, and two kinds of vibrio 

 successfully developed. These differed in size, and are distinguished as 

 hay vibrio a and hay vibrio /?. The larger kind, vibrio a, is a bent 

 rodlct about 3 fx long ; the thickness is about one-fifth of the length. 

 Owing to the ends diminishing in thickness, a crescent-shaped form 

 results, and in the centre of this is a bright spot. Two individuals fre- 

 quently unite to produce an S-like form, more numerous combinations 

 being less common ; but such may appear after eight days' cultivation 

 in bouillon or agar. 



Vibrio (3 is about 2 /a long, and about as thick as the tubercle 

 bacillus. Double-comma forms are very frequent, and in some prepara- 

 tions the rule. On gelatin plates the two kinds grow slowly, but a 

 quicker than (3. Colonies of a attain in three days a diameter of 

 0*2-0 *3 mm., and in six days about 0*6 mm. Under a low power 

 ( X 80) and with reflected light, they appear as circular yellowish-brown 

 discs, and on the third or fourth day as dark rings round about a central 

 point. The colonies of vibrio /3 never exceed ■ 3 mm. in diameter. In 

 neither case is the gelatin liquefied. In gelatin both kinds grow along 

 the inoculation track, and also show a slight growth on the surface, but 

 the whole of the surface is never overgrown. In agar the inoculation 



* Centralis, f. Bacleriol. u. Parasitenk., ii. (1887) pp. 460-72 (2 figs, of a pi.)- 



