OF MICROSCOPIC OBJECTS. 13 
CHAPTER JV. 
PRESERVATIVE LIQUIDS, ETC., PARTICULARLY WHERE CELLS 
ARE USED. 
THERE are many objects which would lose all their distinc- 
tive peculiarities if allowed to become dry, especially those 
belonging to the fresh-water Alga, many animal tissues, 
and most of the very delicate animal and vegetable sub- 
stances in which structure is to be shown. These must be 
preserved by immersion in some fluid; but it is evident that 
the fluid must be suited to the kind of matter which it is 
intended to preserve. As it often requires much study and 
trouble to obtain microscopic objects of this class, it is well 
that their preservation should be rendered as perfect as 
possible; and for this reason the cELLs, or receptacles of the 
fluids, should be so closed that all possibility of escape 
should be prevented. The accomplishment of this is not so 
easy a matter as it might appear to the inexperienced. 
Before giving any directions as to the manipulation 
required in mounting the objects, we must consider the 
different liquids and cells which are requisite for their pre- 
servation. Of the former there are a great number, of which 
the principal may be mentioned. 
DIsTILLED WATER is strongly recommended by many for 
Diatomacesze and other Protophytes. It has been, however, 
stated that confervoid growths often disturb the clearness 
of the liquid, and on this account various additions are made 
to it. A lump of camphor is often left in the bottle, so that 
the water may dissolve as much as possible. One grain of 
bay salt and one of alum are added to each ounce of water; 
or a drop or two of creosote shaken up with an ounce of 
water, which should be afterwards filtered. These additions 
