CHOLERA. 157 



recorders, in order to determine the exact nature of the 

 disease, made plate cultivations from the dejecta of some 

 of the patients, and found Koch's comma bacillus ; they 

 were thus able to put the matter beyond all doubt. How 

 the organism came to the district, and why the outbreak 

 remained localized, are questions that still remain un- 

 answered. During 1890 there was a similar, but less 

 localized, outbreak of fatal diarrhoea in Spain. Koch's 

 bacillus was here again separated, and all doubt as to 

 the nature of the disease at once removed. 



In view of these facts the immense importance of bacteriological methods, 

 as permitting of rapid and definite recognition of the disease, with the possi- 

 bility of taking precautionary measures as early as possible, and so prevent- 

 ing a wide dissemination of the disease germs, can scarcely be insisted 

 upon too strongly. 



In a puncture culture in gelatine the growth takes 

 place along the whole track of the needle, first as a delicate 

 white cloud, then, as it gradually becomes more and more 

 marked, it forms a delicate streak, around which there 

 is usually a clear space, due to the liquefaction of the 

 gelatine along the tract of the needle. Near the surface the 

 liquefaction goes on more rapidly than deeper down, and at 

 the end of forty-eight hours there is a distinct funnel-shaped 

 area, in which a clear liquid portion usually sinks somewhat 

 below the level of the gelatine, and it appears as though the 

 top of the funnel was closed by a small clear glass globe or 

 air bubble. This appearance is apparently due to the slow- 

 ness of the liquefaction, time being given for the water to 

 evaporate from the liquefied gelatine. This is proved by the 

 fact that if S per cent, gelatine instead of 8 or 10 per cent, 

 be used, the gelatine liquefying more rapidly does not allow 

 time for evaporation to take' place, and the bubble is never 

 seen. About the fourth day of the growth this " funnel " is 

 still more marked, but the upper part has become quite clear, 

 the central thread having fallen to the lower and narrower 

 part of the funnel, where it may be seen as a comparatively 

 short spiral, the thread as it sinks being arranged in regular 

 " bights " like those of a cable. After a time the whole of the 

 upper part, say two-thirds, of the gelatine is liquefied and 

 perfectly clear, then comes a layer of " white " cholera bacilli, 

 which rests on the gelatine that has remained solid (this 

 sediment has usually a yellowish tinge) ; and on the surface 



