Abstract
The ability to penetrate a single living cell with very little injury to it by micro-needles and micro-pipettes has proven to be very fruitful in the relatively short time since this technique has been developed by Barber, Chambers, Taylor, and Pèterfi. To be able to penetrate into the interior of a single living cell by means of electrodes that are minute enough and at the same time functional, so that direct and accurate electrical measurements can be made of the electrical conditions attending the stimulation and the normal functioning of a Protisten cell, is obviously of considerable experimental significance.
A micro-electrode of that nature that is non-polarizable has been perfected and tried out by the writer with satisfactory results. Small quartz glass pipettes (about 0.5 mm. in diameter) are drawn out over an oxygen flame to minute points with openings of about 1-2 microns. These pipettes are filled with dialyzed and filtered agar that has been impregnated with M/10 KCl. The agar is dialyzed electrically for the removal of inorganic impurities. The current (D. C.) is sent in both directions for equal periods of time to remove both the anions and cations. It may be stated that the dialyzed agar even after impregnation with KCl, at room temperature is in liquid form (like milk) due probably to the loss of water by the agar because of the complete removal of some anion that is necessary for gelation. The pipettes are sealed into a glass tube (pipette shank) that is filled with the same agar and in which is immersed from the opposite opening a C. P. silver wire coil that has been coated with AgCl by electrolysis. The entire system is made air tight with dental cement and is then suited for mounting on a micro-manipulator.
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