APPENDIX A _ 147 
APPENDIX A 
LABORATORY WORK 
A FEW suggestions may be helpful to those students working along. 
I. The Use of the Microscope.—The flat table, as it were, 
almost in the centre of a microscope is called the ‘ stage.’ Beneath 
this is the mirror that reflects the light on to the stage. Above the 
stage is the tube of the microscope, which can be drawn out. At 
the end of the tube furthest from the stage the eye-piece fits, 
whilst at the other end of the tube, that nearest the stage, the 
magnifying powers are screwed in. 
- The object to be examined is placed on a glass slide, which is put 
on the stage. The mirror is arranged so as to reflect the light on 
to the object, and the observer focuses the draw-tube until he ‘can 
see the object distinctly. Beginners should always work with low 
magnifying powers at first, such as a 2-inch or l-inch. In this 
case the draw-tube has not to be very near the object, and is 
brought into focus by turning the two wheels attached to the tube, 
one on each side. If a high power, such as ; or } inch, is used, 
then the power has almost to touch the glass slide. It is brought 
into exact position by using the smaller wheel, which will be seen 
at the back of the microscope, lower down than the two bigger 
wheels. This smaller wheel should only be used with high powers, 
and not until the object has been brought into focus by the use of 
the larger wheels, which .constitute what is called the coarse 
adjustment, the smaller wheel being the fine adjustment. 
IL. Preparation of Objects for the Microscope.-—When uni- 
cellular organisms, such as Protococcus, are being examined, they 
are generally put on the glass slide in a drop of water, being taken 
up by means of a glass tube narrowed out at one end, called a 
pipette. The finger should be kept over the broad end of the 
pipette when it is being lifted out of the water. ‘The drop of 
water with the Protococcus or other organism having been put 
on the glass slide, a thin circular (or square) piece of glass called 
a cover - glass is placed over it. The cover - glass should be 
