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THE SINGLE CELL CULTIVATION OF YEAST. 



By R. Greig-Smith, D.Sc, Macleay Bacteriologist to the 



Society. 



The method of isolating single cells of yeast by means of the 

 pen, and growing them in tiny drops of nutrient fluid on cover- 

 glasses in a moist chamber, as recommended by Paul Lindner, 

 was a great advance upon the older gelatine process as practised 

 by Hansen. The Lindner-method is in general use at the pre- 

 sent time. It has some disadvantages, however, as will be 

 recognised when the method, which I am about to describe, has 

 been tried. 



The pen acts by the capillary nature of its split, and it is a 

 simple step to adopt a glass capillary, such as may be obtained 

 bv drawing out a heated piece of glass tubing until the tube is 

 of the necessary bore. A four-inch piece of glass tubing of 4mra. 

 bore, heated in the bunsen flame until soft, and drawn out to 

 about thirty inches, will furnish several suitable capillaries. 

 The heating sterilises the glass, and the capillary is ready for 

 use when broken or cut into short lengths of, say, five inches. 

 It is better to cut the capillary with a fine file to ensure a clean 

 cut. A broken end will not make a good contact with the 

 cover-glass, when the yeast-suspension is spotted. If the hand 

 is used to cut or break the tube, the capillary can be sterilised 

 bv passing it rapidly through the flame before using. 



The capillary is dipped into the suspension of yeast-cells, and 

 inclined at an angle. The liquid rushes up the capillary but 

 soon stops. The capillary is withdrawn, and 16 to 20 spots are 

 dotted upon a sterile cover-glass, just as in the Lindner-method. 

 The size of the spot can be regulated by inclining the capillary 

 more or less to the vertical, and by the duration of contact with 

 the cover-glass. The aim is to have the spot of such a size as 

 can be included in the field of the microscope. 



