﻿308 The Philippine Journal of Science ww 



INTRODUCTION 



Since the classical work of Hansen in isolating single cells of 

 yeast plants, various methods of isolating single organisms under 

 microscopical control have been described. In the method of 

 Lindner, employed chiefly in the isolation of yeast cells or rela- 

 tively larger organisms, droplets of a highly diluted culture are 

 placed on a cover glass with a fine, sterile drawing pen. The 

 preparation is placed over a moist chamber and examined for 

 a droplet containing a single organism. In the well-known 

 method of Burri,^ a dilution of the organisms is made in India 

 ink. With a sterile drawing pen, fine droplets are placed on 

 solidified gelatin, and a cover glass is placed over them. The 

 contrast between the organism and the dark background makes 

 it possible to distinguish the organisms clearly and to find a 

 droplet which contains but a single one. The organism is left 

 to form a colony in situ, or the cover, with the organism clinging 

 to it, is transferred to any desired medium. In the method of 

 Schouten,^ the single organism is picked out from a dilution by 

 means of a very fine glass loop in a moist chamber and under 

 microscopic control. 



The method described here is founded on a principle wholly 

 different from any of those described above. No preliminary 

 dilution of the microorganisms is necessary, except such as may 

 be carried out under the microscope at the moment of isolation, 

 and this dilution is required only in relatively dense suspensions. 

 I first used the method in 1902 in connection with the selection 

 of yeast plants. The description of the method was first pub- 

 lished in 1904 * and more fully in 1907.^ It was, so far as my 

 knowledge extends, the first method of isolating organisms under 

 microscopic control described since that of Lindner. Since the 

 first publications of the technique, various modifications and im- 

 provements have been described in later papers. The chief aim 

 of this article is to bring together these various descriptions and 

 to add considerable material not before published. 



The method has been introduced into a number of laboratories, 

 and it is hoped that this description may lead to its wider use. 

 It is believed that the method has a universality of application 

 which will make it of use not only to bacteriologists, but also 

 to workers in all departments of microscopy. Single bacteria 



■Das Tuscheverfahren. Jena. Gustav Fischer (1909). 

 ' Zeitschr. f. wiss. Mikros. (1905), 22, 10. 

 * Journ. Kans. Med. Soc. (1904), November. 

 'Sd. Bull, Kansas Univ. (1907), 4, 3. 



