267 
XIV.— THE PLUNGER-PIPETTE— A NEW INSTRUMENT 
FOR ISOLATING MINUTE ORGANISMS. 
By Professor A. Brooker Klugh, Biological Dept., 
Queen’s University, Kingston, Canada. 
{Bead June 21 , 1922 .) 
One Text-Figure. 
During the summer of 1921 I had occasion to isolate a large 
number of unicellular algse for the production of pure cultures, 
and this instrument, which I have named the Plunger-pipette, was 
originated to do this work with precision and celerity. 
This instrument consists of: — (1) a piece of thin , soft glass 
tubing drawn to a capillary tube at one end ; (2) a glass plunger 
drawn from a piece of glass rod to sufficient fineness to fit the 
capillary tip, and with a flattened knob at the other end ; (3) a 
piece of rubber tubing which is placed so as to project beyond the 
glass tube. 
In the figure the capillary tube is, for the sake of clearness, 
shown as relatively coarse, but in practice this tube should have 
an inside diameter of 80 micra or less. 
"Pl-unge-r 
Head , 
These parts are so adjusted that the end of the plunger inside 
the capillary is about 1 mm. from the end of the capillary, while 
the knob rests against the rubber. This is accomplished by insert- 
ing the plunger (which should be made with the fine-drawn 
portion longer than required), and cutting off the part which 
projects through the capillary, then making the fine adjustment 
by moving the rubber slightly upwards. 
The manner of using this instrument is as follows : — A drop 
or two of water containing some of the organisms it is desired to 
isolate is placed on a slide, the organism located, and examined 
with the 4 mm. objective and a X10, or higher, ocular. The 
desired organism is then located under the 16 mm. or 8 mm. 
objective. The pipette is held with the thumb and second fmger 
just in front of the rubber, while the plunger-head is pressed with 
