96 NATURALISTS’ ASSISTANT. 
tage to import the lenses of either Hartnack or Zeiss and 
have them fitted by an “adapter” to his microscope. By 
this method, he will obtain good objectives at about half the 
prices charged for similar lenses of no better quality made 
by American opticians. 
Binocular microscopes have of late been extensively ad- 
vertised, but for work possess not the slightest advantage and 
are only manufactured so that the makers may add to the 
prices and to the profits made on their instruments. 
THE USE AND CARE OF THE MICROSCOPE. 
It is a difficult task to give directions for the use of the 
microscope as the varying uses to which it is put require as 
varied a method of handling. All objects for the micro- 
scope should be mounted either temporarily or permanently 
on a glass slide. If it be a moist tissue or an object taken 
from the water, a drop of water should be placed on the 
slide, the cbject placed in it and the whole covered with a 
piece of thin glass. The slide and its object are now ready 
for examination. The microscope should now be made ready 
and the objectives screwed on. It is best to use first the 
lower powers and then the higher if necessary, with either 
reflected or transmitted light according as the object is 
opaque or transparent. There are several advantages con- 
nected with this method of treatment, one being that in this 
way a general idea of the structure is first obtained and the 
various details are studied afterward. It is also much easier 
