METHODS FOR PREPARING MICROSCOPIC OBJECTS. 13 



should be packed in its box, and the accessories may also be 

 kept in a suitable chest, such as has been described, and which 

 is made by a number of opticians. 



After the directions that have been given, it seems hardly 

 necessary to add that everything pertaining to the work should 

 be carefully cleansed after using, and put away in its proper 

 place, so as to be immediately available at any future time. 

 The expenditure of a little time in these details is more than 

 counterbalanced by the greater rapidity and effectiveness of 

 subsequent work. 



How to pr&pare afresh microscopic object for rapid exam- 

 ination. When practicable, every specimen should be studied 

 as early as possible after removal from the body, and this is 

 important even if it is to be hardened and prepared for per- 

 manent preservation. 



Take a clean slide, which, of course, should be reasonably 

 thin ; place it before you upon a white ground (some micro- 

 scopists have a square plate of marble set into the table); mois- 

 ten the slide with a drop of some indifferent fluid, such as 

 iodized serum or, perhaps, a three-fourths per cent, aqueous 

 solution of common salt ; then place in the drop the fragment 

 to be examined. Small particles are more easily studied than 

 large ones. Usually the substance should be spread out a 

 little with needles. 



In one or two minutes it is ready for examination. By this 

 method striped muscular tissue may easily be detected ; and it 

 also happens to be a good example because it is very frequently 

 brought to microscopists for examination. In certain forms of 

 dyspepsia, especially in women, it is common for ingested 

 meat to pass through the alimentary tract with very little 

 change. Prepared for the microscope in this simple way the 

 peculiar markings of striped muscle may be observed at once, 

 and even if the meat has been boiled. 



If, however, the material to be examined is opaque, we add 

 to the drop of serum another of glycerine ; the latter alone re- 

 fracts the light too much, and is therefore undesirable. When, 

 however, it is combined with an equal amount of serum or the 

 salt solution, the fluid has a proper refractive power for most 

 histological purposes. The microscopist should now let fall 

 upon the drop a cover glass, and place the slide upon the stage 

 of the microscope. Nothing is required to keep the cover in 



