The writer has three reasons for introducing what, to many workers,
is a somewhat threadbare subject: (l) In the minds of not a few
people with whom the author has discussed the matter, the impression
still persists that the technique of the isolation of single bacterial
cells is extremely difficult, involving months, if not years, of practice
for its successful acquisition. Heller (1921) stated that she found
the Barber (1914) method "wasteful of time, material, eyesight and
nervous energy" in the isolation of anaerobic bacteria. There is
some justification for saying that a wastage of time and energy
occurs when, after the successful isolation of ten to twelve bacteria
or spores, not one germinates. This point, the germination of the
single germ, especially when it concerns the anaerobes has not
received the same amount of attention that the actual isolation has.
The latter is a simple mechanical process, the former one over which
the operator has not the same degree of control. (2) A method of
isolation, to be of real practical value and to enjoy a constant and
wide application, must be simple and devoid of tedium and time
wastage. Preferably should it be such that the worker would prefer
to employ it rather than use plate or shake methods of isolation.
Again, the learning of the technique should not require months of
practice nor should it be of such a nature that only those people with
"hands" can easily acquire it. Reyniers (1933) described a method
by which beautiful micro-pipettes may be made mechanically. The
writer gained the impression, wrong, he hopes, that the making of
the apparatus would be one requiring considerable skill and time.
Doubtless, however, to see the designer himself at work would dispel
this idea. The method, used by the writer for over four years, has
proved to be so simple that three colleagues, after half-an-hour's
practice in pipette-making have settled down and isolated (with
successful germination) single germs of Cl. welchii and B. anthracis.
(3) The third reason advanced for the presentation of this note is in
the nature of a plea for the more extended use of the single cell
isolation method as a routine measure. The saving of labour and
of time involved in obtaining definitely pure cultures and the feeling
of assurance in having these pure cultures greatly outweighs the
only disadvantage (in the writer's opinion) of the expenditure of
the money for the micromanipulator. But even a machine costs no
more than a good microscope and where the outlay is impossible a
locally-made apparatus or the modification used by Malone (1918)
may be employed. Finally, there is the possibility that less would
be heard of bacterial mutation if cultures were first purified by the
The making of Micro-pipettes. On the making of satisfactory
pipettes depends the success of isolation. The writer was quite
unable to make an efficient article by the "tiny flame method" as
described by Barber (1914) and Chambers (1922). That this method
gives highly satisfactory results there is no doubt; never having had
the procedure demonstrated to him and the use at these laboratories
of "paraffin gas" (Mansfield system) are doubtless the reasons for
the failure. The electrical heater described (Mason 1933) solved the
difficulty. The two elements, arranged in the form of a V, may be
made broad or narrow. If narrow, the type of pipette most desirable
for isolation work is easily prepared. It is advantageous that the
micro-portion should not be more than 1.5 to 2 cm. long and that it
should leave the thick portion of the hand drawn capillary sharply.
A long tapering micro-pipette trembles easily and when raised against
the cover slip in the process of isolation "gives" considerably,
necessitating much adjustment of the control screws of the machine.
Such a tapering pipette is liable to be pulled when the breadth of
the elements is 3.0 cm. or more. Elements of 2.0 cm. give satisfactory
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