﻿IX, B, 4 Barber: The Pipette Method 309 



of any degree of motility or of any size visible under an ordinary 

 oil-immersion lens, yeast cells, spores of fungi, algae, protozoans, 

 blood corpuscles, or other histological elements may be isolated. 

 A cell may be selected from a pure culture or from a myriad of 

 other organisms larger or smaller than itself. Organisms may 

 be selected from cultures or from the natural sources, and the 

 whole process may be carried out in any fluid desired. The 

 isolated organism may be cultivated in situ, transferred to any 

 medium, or inoculated into an animal. Microorganisms, stains, 

 fixatives, or other chemical substances may be injected into the 

 protoplasm or vacuoles of living cells. Microscopic plants, 

 animals, or histological elements may be dissected or stained 

 under the higher powers of the microscope. 



The isolation of organisms and some of the other applications 

 of the technique may be carried out with the aid of only the 

 ordinary apparatus of a biological laboratory. 



Since the earlier publications, I have had much experience 

 in teaching the method to others. The difficulties of the 

 technique are certainly not insurmountable, since several learners 

 have, under my direction, succeeded in making pipettes 

 and isolating organisms after less than an hour's practice. The 

 results of this experience in teaching have shown me some of 

 the chief difficulties of the beginner, and it is hoped that the 

 following description will make the technique easy to acquire 

 without the assistance of personal supervision. 



In some cases details have been given which may seem super- 

 fluous to many workers, but it was thought better to err on 

 the side of over description than to risk leaving any point 

 obscure. 



The method of isolation of microorganisms described here 

 is, of course, not recommended as an entire substitute for plate 

 methods in any routine work. In some cases the pipette method 

 may be conveniently used as such, but the chief aim of .this 

 technique is to amplify the plate method and to carry out some 

 isolations where the plate method is not applicable. 



ISOLATION OF MICROORGANISMS 

 GENERAL PRINCIPLE 



The principle of the method, in brief, consists in the separation 

 of the single organism by means of a very fine-pointed, capillary 

 pipette of glass. The isolation is carried out in hanging drops 

 on the underside of a large cover glass which is placed over a 

 moist chamber. The organism to be isolated is touched with 



