536 



Dr. P. F. Frankland. 



[June 10, 



the needle becomes visible as a fine thread, which sooner or later is 

 followed by a conical depression at the surface ; this depression is 

 filled with air at its wider upper extremity, and slowly increases in 

 width ; as growth proceeds the track of the needle becomes thicker, 

 and the air-cavity at the surface becomes partially filled with clear 

 liquid, at the bottom of which there is a whitish somewhat flocculent 

 precipitate. 



The growth in peptone-broth is very rapid, the liquid becomes 

 turbid, and on the surface there is formed a tough pellicle which 

 increases in thickness, whilst the subjacent liquid is again clarified. 



Appearance of K.ocJis Comma Spirillum in Gelatine-plate Cultivations. 



The plate cultivations exhibit in the course of two or three days 

 minute whitish spots, each situated at the bottom of a small depres- 

 sion on the surface. The colonies remain small, but when very 

 numerous the substance of the gelatine becomes largely liquefied. 



Magnifying power nearly 1000. Magnifying power about 100. 



Under the low power of the microscope the colonies present the 

 appearance of somewhat irregular disks, with a more or less irregular 

 and jagged edge, the interior of the disk being filled with coarsely 

 granular matter. 



Multiplication Experiments with Specific Organisms. 



The pure cultivations of the three specific organisms mentioned 

 above were introduced into the experimental waters in the following 

 manner, so as to secure a degree of attenuation which admitted 

 of satisfactory examination by plate cultivation. 



One or more needlefuls of the cultivation are fiist inoculated into 

 about 50 c.c. of sterilised distilled water contained in a sterile stop- 

 pered bottle; this first attenuation is then well shaken, so as to 

 distribute the introduced organisms evenly throughout. From this 

 first attenuation a certain number of drops are withdrawn by means of 

 a sterilised pipette, and introduced into the sterilised experimental 

 water contained in another sterile stoppered bottle. The latter is then 

 in turn well shaken, and the number of organisms in a given volume 

 determined by plate cultivation. This second attenuation is then 

 exposed to any desired conditions of temperature, &c, and the 

 number of organisms debermined in it at suitable intervals of 

 time. 



