io THE BACTERIA IN ASIATIC CHOLERA. [CH. 



"When the colony becomes somewhat larger, this granu- 

 lation becomes more and more evident ; at last it looks like 

 a little heap of strongly refracting granules. I might best 

 compare the appearance of such a colony to the appearance 

 of a little heap of pieces of glass. As they grow, the 

 gelatine liquefies in the immediate neighbourhood of the 

 bacteria-colony, and this latter sinks down at the same time 

 deeper into the mass of gelatine. A funnel-shaped cavity is 

 thus formed in the gelatine, in the midst of, which the colony 

 is seen as a little whitish point. This appearance is also 

 quite peculiar ; it is seen, at least in this manner, in very few 

 other kinds of bacteria, and, as far as I know, never so 

 marked as with the comma-bacilli. The sinking of the 

 colonies can be best observed when carrying out an artificial 

 cultivation. A suitable colony is selected on the gelatine- 

 plate under a microscope with a glass of slight magnifying 

 power; it is touched with a platinum-wire, previously heated; 

 the bacilli -are transferred by the wire into a test-tube with 

 gelatine, and this is closed with sterilised wadding. A 

 cultivation of this kind then grows in the same manner as 

 the colony on the gelatine-plate. I am in possession of a 

 numerous collection of artificial cultivations of bacteria 

 made in this manner ; but I have never seen in their case 

 such changes as the comma-bacilli cause after being trans- 

 ferred into the gelatine. Here, also, as soon as the cultiva- 

 tion begins to develop you see a little funnel, which marks 

 the point where the inoculation took place. By degrees, the 

 gelatine liquefies in the neighbourhood of this point of 

 inoculation ; then the little colony is plainly seen, extending 

 itself more and more ; but a deep spot, sunken in, always 

 remains, which looks, in the partially liquefied gelatine, as if 

 an air-bubble were hovering over the colony of bacilli. It 

 almost gives one the impression that the bacillary growth not 



