221 



VI [. — The Isolation of the Single Bacterial Cell. 



By Nathan Mutch, M.A., M.D., M.R.C.P. 

 (From the Bacteriological Laboratory, Guy's Hospital.) 



{Read March 19, 1919.) 

 One Text-Figube. 



The ideal starting point of a " pure " cultivation is without doubt 

 the single " spore " or the single vegetative cell, and in the case of 

 a comparatively large organism such as a yeast it is easy of attain- 

 ment. But the problem becomes increasingly difficult with the 

 diminution in size of the bacterium to be studied ; and in planning 

 any method to attain the desired end three points need 

 consideration. 



1. A single organism must be separated from its fellows in a 

 small quantity of medium. 



2. This single organism must be placed under such conditions 

 that it can multiply and produce a massed growth capable of being 

 manipulated by ordinary bacteriological methods. 



3. The original observation that one organism, and one only, 

 was separated from the rest must be capable of confirmation. 



Several methods for the isolation of the single cell have already 

 been described, and many of them were tried out but discarded ; in 

 particular, much time and patience was expended on that recently 

 described by Malone,* which necessitates the use of a teat capillary 

 pipette to suck up a minute drop of water containing a solitary 

 cell, whilst observing the process microscopically. 



Failure usually resulted owing to the difficulty of illuminating 

 the process satisfactorily, also because the end of the pipette merely 

 indents the shallow drop of water and the lips of the orifice do not 

 become wet, so that the drop remains on the slide and will not 

 enter the capillary tube. 



The method to be described avoids many of these difficulties, 

 is simple and easy, and requires no elaborate or special apparatus. 



Apparatus Required. 



Microscope with \-m. and yV"^'^- lenses. 



Artificial illuminant. 



" Hanging drop " slides : prepared by cementing tin alloy rings 



♦ Journal of Pathology and Bacteriology, 1918, 22, 222-3. 



