﻿322 The Philippine Journal of Science mm 



cess, including the drawing out of the capillary and the making 

 of the point, the adjustment under the high power, and the isola- 

 tion of a micrococcus, in less than three minutes. 



Recapitulation of the various steps in the isolation of bacterium 

 by method I: 



1. Clamp the pipette holder in position on the microscope. 



2. Prepare the moist chamber. 



3. Prepare and sterilize the cover glass. 



4. Seal the cover glass to the moist chamber and mark its 

 upper surface. 



5. Place under the cover glass hanging drops of sterile nutrient 

 fluid, and supply one of them with the bacteria to be isolated. 



6. Place the moist chamber on the stage of the microscope, and 

 focus on its free edge with the low power. 



7. Make the capillary pipette. 



8. Attach the rubber tube to the pipette, and adjust the pi- 

 pette in the holder with its tip in focus under the low power. 



9. Supply the pipette with sterile nutrient fluid from a hang- 

 ing drop, and adjust it in the center of the high-power field. 



10. Take up the bacteria and isolate them in separate droplets. 



METHOD II 



Some investigators may wish to obtain one-cell cultures of 

 bacteria, fungi, algae, or microscopical animals without having 

 occasion to do more extended selections. Such persons may 

 hesitate to go to the delay and expense of obtaining a pipette 

 holder. The following method will enable the worker to obtain 

 pure cultures with the assistance of only such apparatus and 

 materials as are found in every laboratory. The technique is 

 but slightly more difficult, and very precise results may be 

 obtained. The preparation and setting up of the apparatus 

 needed may be done in one or two hours, and the technique may 

 be mastered by an ordinarily skillful laboratory worker in half 

 a day or less. 



The moist chamber, cover glasses, and tubing are the same 

 as those used in the first method. In place of the pipette 

 holder, an ordinary dissection microscope, supplied with rachet 

 and pinion, is firmly clamped to the table as far from the edge 

 as the clamp will allow (fig. 7). The arm of the lens holder is 

 turned backward, and on it a rectangular perforated cork is 

 firmly fastened with a clamp or rubber bands. The opening in 

 the cork should be large enough to hold the glass tubing snugly, 

 but not so firmly as to prevent the slipping of the tube back and 

 forth. The capillary and tip are made as in the first method, 



