OF MICROSCOPIC OBJECTS. 12$ 



CHAPTER V. 



PRESERVATIVE LIQUIDS, ETC., PARTICULARLY WHERE CELL* 

 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 Algse, 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 

 Diatomacese 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 



