156 BACTERIA. 



bottom of these depressions yellow pin-like masses are 

 usually seen. In consequence of this liquefaction the colony 

 has the appearance of a piece of ground glass with a finely 

 notched margin surrounded by a clear zone. On the second 

 or third day small air bubbles are seen, and on the fifth or 

 sixth day the liquefaction is well marked ; at this stage the 

 colony has sometimes a delicate pink tinge, a most charac- 

 teristic feature when present. From these points or colonies 

 growing, as we have seen, from individual organisms or 

 small groups of the bacillus, pure cultivations may be made 

 in test tubes containing gelatine, agar-agar, potatoes, or 

 broth in or on .which the growth and special characters of 

 the bacillus may be watched and noted. It is sometimes 

 made a matter for reproach to bacteriologists that the 

 methods employed in their work, useful enough though 

 they may be in conducting scientific experiments, are found 

 altogether wanting when they are required for actual prac- 

 tical work. The following story, which went the round of 

 the medical papers, may help to remove the idea that bac- 

 teriologists are mere visionaries, and to prove that the 

 science, some of the problems of which they are at- 

 tempting to solve, is by no means so useless as many would 

 have us believe. An Italian emigrant steamer, touching 

 at New York, had on board a child suffering from a sus- 

 picious form of diarrhoea, though it could not be said that 

 all the symptoms of Asiatic cholera were present. In order 

 to determine the true nature of the disease — whether it was 

 cholera or not— ^gelatine plate cultivations of the dejecta 

 were made by a doctor in port, and the vessel was detained 

 for four days ; during that period bacilli identical in ap- 

 pearance with, and having all the characteristics of, Koch's 

 comma bacillus were developed, and it was at once con- 

 cluded that this was a case of true Asiatic or Indian cholera. 

 The diagnosis was subsequently confirmed, as a series of 

 other cases occurred, in all of which unmistakable symp- 

 toms of Asiatic cholera were developed. An equally in- 

 teresting and instructive example of the- same thing was 

 recorded by PfeifFer and Gaffky when they were working in 

 Koch's laboratory. At a time when there was no general 

 cholera epidemic, Gonsonheim and Finthen in Germany were 

 suddenly ravaged by a most deadly form of diarrhoea which 

 in many features resembled true Asiatic cholera. The 



