SINGLE-CELL ISOLATION 101 



for single-cell isolation has been described in former 

 editions of this book (e.g. the sixth edition, 1918, p. 93). 

 A better and simpler method is that of Mutch. 1 Cells are 

 required consisting of rings of ebonite, glass or metal 

 cemented to glass slides. Rings of filter paper are cut by 

 means of two hollow punches (cork-borers will do) of 

 such a size that they will lie inside the cells ; these are 

 placed in position within the cells and moistened with 

 saline. A very thin emulsion of the organism is prepared 

 and a minute droplet of it is deposited on a cover-glass, 

 previously sterilised by flaming. The preparation is 

 rapidly mounted on a vaselined cell so as to form a 

 hanging-drop preparation. The drop is then examined 

 with a J in. or -| in. objective. If but a single organism 

 is present, the cover-glass is raised from the cell, a drop 

 of melted gelatin or agar is placed on it and mixed with 

 the droplet of emulsion, and the cover-glass is mounted 

 on another moist cell and incubated. When the colony 

 has developed sub-cultures may be prepared. By the use 

 of saline for moistening the filter paper in the cell, the 

 drop neither shrinks nor grows. Hort has also described 

 methods of single-cell isolation (Journ. of Hygiene, 1919). 

 Barker 2 has devised a method by which a single organ- 

 ism or cell can be picked up with a capillary pipette. 

 The fluid containing the organisms and suitably diluted 

 is mounted on the under surface of a cover-glass forming 

 the roof of a special cell. The capillary pipette is mounted 

 on a stand provided with three screws by means of which 

 motion in the three directions of space can be obtained. 

 The film is examined microscopically and a suitable 

 organism having been found the pipette is brought into 

 position and the organism taken up into it. 



1 Journ. Hoy. Microscopical Soc., 1919, Pt. 3, p. 221. 



2 See Philippine Journ. of Science, vol. ix, Sec. B, 1914, p. 307. 



