42 KANSAS UNIVERSITY SCIENCE BULLETIN. 



dimensions found most convenient for this box are 40 mm. 

 long by 25 mm. wide by 18 mm. high, though various other 

 dimensions have been successfully used. The sides of the 

 box are lined with filter-paper extending nearly to the top 

 and projecting a few millimeters beyond the open end. A 

 small rod may be inserted at the base of the open end to 

 strengthen the apparatus. 



Before making isolations, the filter-paper is thoroughly wet, 

 and a 25x40 mm. cover-glass, previously well cleaned, is 

 sterilized in the flame and placed on the box, to the upper 

 edges of which vaseline has been previously applied. On the 

 sterile under surface of the cover-glass a drop or two of the 

 sterile nutrient fluid to be used is placed by means of a steril- 

 ized platinum loop, and near it a drop of the culture con- 

 taining the organisms to be isolated. The whole is then 

 placed on the stage of the microscope, a. A capillary 

 pipette, h, is then made by drawing out in the flame a thin- 

 walled glass tube, 8 to 10 cm. in length and about 4 mm. in 

 diameter, in such a way that one end becomes a fine tube, 

 with walls as thin as possible. Holding the thicker end of 

 this tube in one hand and the capillary end with sterilized 

 forceps in the other, the capillary tube is again drawn out 

 over a very small flame, and, just at the moment of drawing, 

 a turn may be given with the forceps so as to form a tip, 

 curved nearly at right angles with the rest of the tube, or the 

 capillary tip may be made straight and afterward bent in the 

 heat of the flame. It is important to have the aperture of 

 this curved tip very small, especially for work with bacteria. 

 I have used pipettes of such dimensions that the opening 

 would admit the smaller yeast cells, but not the larger. If 

 the pipettes are made much smaller than this, capillarity 

 may be so great as to prevent the discharge of liquid from 

 the opening. It is often convenient to make a number of 

 these pipettes, sterilize them in the hot-air sterilizer, and 

 keep them in sterile receptacles ready for use. 



In the latest type of this apparatus the thicker part of the 

 pipette is held with a brass holder, clamped on the left side 

 of the stage. The box, held in the mechanical stage with its 

 open end towards the pipette holder, is adjusted so that the 



