AGf~ICULTURAL RESEARCH, PUSA.

THE USE OF THE MICROSCOPE 55
have some form of microscope lamp which partially
encloses the bulb, so that no glare reaches the eyes. It
is not advisable to lIse the microscopc at a window, as the
daylight entering the eycs renders the vision less acnte.
A suitable anangemcnt is to use the microscope on a
small table at one side of the room so that the observer's
baek is towards the window.
Whcn cxamining an object, the manipulations of
the microscope should be carried out ill thc following
order:
(1) Set up the microscope, place the objcet on the
stage, and adjust the plane side of the mirror
to the illumillant so that light is l'eHeeted
into the condenser.
(2) Focus the specimen with the low-power objcctive,
using the coarse adjm;tment.
(3) Manipulate the mirror until the image of the
illuminant is seen in the centre of the Held;
lower the condenser so that the whole field is
evenly illumirw .. ted.
(It is essential, particularly WhCll cxamining
tissues, to use the low-power first, in order
to locate organisms and observe the tissue
changes. A suitn.ble field having been obt.ained,
the slide must be kept in place by
means of the right-hand clip if a mechanical
stage is not used.)
(4) Rack up the objective a short distance and
place a drop of cedar-wood immersion oil on
the portion of the specimen immediately below
the objective.
(5) Raise the condenser so that its upper surface
is practically level with the stage, and makc
sure that the iris diaplll'agm is widely open.
(6) Rotate the nose-piece until the oil-immersion
lens is in position.
(7) With the eye at the level of the stage lower the
objective by means of the coarse adjustment
until the lens is seen just to touch the oil.
(8) Apply the eye to the microscope and observe