CHAPTER I 
APPARATUS 
The amount of apparatus required for histological work varies, 
temporary mounts, glycerin mounts, and freehand sections requiring 
only a razor and a microscope, while the paraffin method, which 
represents the highest development of technic, brings into use nearly 
all the equipment of the histological laboratory. The following list 
includes only the apparatus necessary for making preparations: 
a microscope; a microtome; a razor; a hone and a good razor strop; 
a paraffin bath; a turntable; a scalpel; a pair of needles; a pair of 
scissors; a pair of forceps; staining-dishes; solid watch glasses; 
bottles; a graduate (50 or 100 c.c.); pipettes; slides, 1X3 inches; 
round covers, 18 mm. or f inch in diameter; and square covers, £ inch. 
Longer covers will be needed for some of the serial sections. 
A microscope should have a rack and pinion coarse adjustment, 
a fine adjustment, two eyepieces magnifying about four and eight 
diameters, a low-power objective of about 16-mm. focus, and a 
high-power objective of about 4-mm. focus, a double nosepiece, an 
iris diaphragm, and an Abbe condenser. A cheap and practical 
form is shown in Figure 1, and similar instruments are for sale by all 
the leading companies. 
Since the chemicals used in histological technic are likely to 
damage the stage and substage of the microscope, it is well to place 
upon the stage a piece of glass 3 or 4 inches square. A lantern- 
slide cover is just right for this purpose. It is not necessary to fasten 
it to the stage, since it is merely for protection while examin¬ 
ing slides which are wet with reagents. In our own laboratory we 
use for examining wet slides a cheap microscope with only a single 
low-power objective and a single ocular. 
Some knowledge of the structure and optics of the microscope is 
necessary if one is to use it effectively. Why are there so many 
diaphragms ? Why is there an arrangement for raising and lowering 
the condenser ? Why does the mirror bar swing ? Why is one side 
of the mirror plane and the other concave? Everyone who uses 
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