PIPETTES FOR HOLDING AND MEASURING FLUIDS. 
CHARLES A. BEHRENS. 
(Purdue University, Lafayette, Ind.) 
There are many applications in bacteriology and especially in serology 
for pipettes which will serve the double purpose of holding and measuring 
fluids. We have devised such pieces of apparatus which are simple in con- 
struction, easy and convenient to operate and which have proved to be 
satisfactory in our laboratory. 
Figure I represents the pipette for use when it is desired to handle sterile 
liquids. The glass parts and rubber connections are sterilized in the usual 
way and assembled aseptically. 
By releasing the clamp (C) on rubbering-tubing connection (D) the 
sterile fluid contained in the reservoir (B) which may be of any suitable 
shape, will flow into the pipette (G) which is of the desired calibration. 
The side-arm (FE) which is plugged with sterile cotton (F) to avoid air 
contamination, compensates for the air displaced by the liquid entering 
the calibrated tube (G) or replaced when the clamp (J) on rubber-tubing 
connection (I) is released thus permitting the measured fluid to flow 
thru the ecapillary-tubing (K). The latter may be protected by a sterile 
test-tube (M) plugged with cotton (1). 
Applying negative or positive pressure by means of the rubber-tubing 
(H) which is connected to the side-arm, the liquid which remains in the 
capillary-tubing or pipette proper or in both may be removed. The small 
amount of sterile liquid which may be discharged from time to time from 
the same may be collected in sterile tubes or flasks and thus prevent waste 
of fluid. However, it is not advisable to return such material to the stock 
solution in the reservoir for fear of contamination. 
After the opening in the capillary-tubing has been sealed in the flame 
the liquid is stored by placing the appartus in the refrigerating-room. When 
more fluid is to be used a file-scratch is made near the sealed end of the 
capillary-tubing. It is broken off, the opening sterilized by flaming and the 
pipette is manipulated as before. It may be advisable to warm the liquid 
before so doing. Of course, sterile fluid may be taken directly from the res- 
ervoir. 
Evaporation of the material may be cut down to a negligible quantity by 
covering the cotton stopper (A) in the holding-chamber with a rubber cap 
or by inverting a test-tube over it etc., and by tying a knot in the rubber- 
tubing (H). 
In this way a sterile liquid may be conveniently stored with a minimum 
amount of evaporation and used in definite quantities without becoming 
contaminated. 
In serological work where sterility is not necessary but where it is 
essential to bring the reacting substance to an equal volume by adding 
physiological salt solution the pipette as shown in figure II may be used 
to an advantage because of its convenience in operation and time saving. 
The apparatus is entirely glass in construction and in operation is similar 
to the pipette previously considered. A rack holding the tubes containing 
the reacting substances is placed under the pipette and the required amount 
of physiological salt solution is added to each tube. 
