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SINGLE CELL CULTIVATION OF YKAST 



distributed a condition tliat one cell can generally be found in 

 every second drop. It is as if the cells had been counted auto- 

 matically. There will naturally be limits to the method: I have 

 not tried a yeast-paste, nor yet a very dilute suspension, but, 

 with an ordinary opalescent suspension, my students have always 

 been successful with the second dilution. 



It is sometimes advisable to break down the yeast-agglomer- 

 ates by Wright's method of breaking down bacteiial clumps. A 

 ball-pipette, drawn out to a capillary point and furnished with 

 a strong rubber-bulb, is used for alternately sucking and blowing 

 the suspension. This is followed by a gentle centrifugalisation, 

 so that the heavier clumps are sedimented while the single cells 

 remain in the fluid. 



When the single cells have produced a sutticient progeny, the 

 cover-glass is removed, and the droplet touched with a capillary. 

 The fluid runs up the tube with the yeast-cells and the capillary 

 is then inserted into a flask of wort, and the end broken off. It 

 is usual to pick up the capillary with sterile forceps, pass it 

 rapidly through the flame, allow it to cool, touch the droplet, 

 insert into the flask, and snap off the capillary with a pressure 

 of the forceps against the side of the flask. 



The use of the capillary and the tube-method of dilution have 

 been very successful in reducing the time occupied in preparing 

 sinorle-cell cultures. 



