956 Transactions of the Society. 



is the funnel-sliaped depression of the liquefied gelatin, surmounted 

 by an air-vesicle. Cultivated in nutrient agar-agar at whatever 

 temperature, it grows as a light scum on the surface, it does not 

 liquefy the material, and there is nothing at all characteristic in its 

 usual habit of growth, though it is in this medium, as above stated, 

 that the remarkable method of multiplication by longitudinal fission 

 occurs. 



It developes equally well in neutral and faintly alkaline media, 

 but it will also develope in distinctly acid infusions, as in 1 per 

 mille of free hydrochloric acid, though here uncertainly and slowly. 

 It grows equally well, too, though not with the same rapidity, at 

 different temperatures between 10° and 35° C, and is, as emphasized 

 by Koch, rapidly killed by desiccation. 



The cultivations which I originally obtained from Dr. Eoux 

 of Paris, through the kindness of Dr. Maddox, show both by their 

 characters in nutrient gelatin, and by direct comparison of dried 

 and stained specimens of Dr. Koch, identically the same characters ; 

 they are also the same as those of Dr. Klein. 



The habits of growth of micro-organisms in solid cultivating 

 media, have lately received much attention, and it was thought 

 that here we had a ready and sure means of specific diagnosis, 

 more sure and more distinctive as has been asserted, than the 

 microscopical characters of these organisms. To my observation 

 this is entirely erroneous ; there are scarcely two species of the lower 

 fungi, excluding perhaps micrococci, which may not be distinguished 

 by competent microscopical examination, with adequate means. 

 When a similarity of form and minute characters does occur, then 

 observation of their growth may come in, but only as an auxiliary 

 and secondary means of diagnosis; it cannot be of primary im- 

 portance, because, firstly, the characters or appearances are not 

 constant under slightly different conditions, and secondly, because 

 different species of totally different form, as readily recognized 

 under the Microscope, grow in identically the same manner in these 

 cultivations, one instance of which I showed to this Society on a 

 former occasion, and hope to illustrate the subject further on a future 

 opportunity. The same thing applies equally to the characters of 

 the colonies on the surface of gelatin on glass plates, or in cells, 

 so that this means of diagnosis has only a very limited application 

 and utility. As a method, however, of separating different species, 

 and thus originating " pure " cultivations — the necessary basis for 

 all exact observations on this subject — it is absolutely invaluable, 

 and is in most cases far more rehable and less laborious than 

 " fractional dilution." 



It is, however, to its relations to Asiatic cholera that is due the 

 interest which this microbe has excited and continues to excite 

 throughout this country, the Continent, and indeed a large portion 



