OF MICROSCOPIC OBJECTS. 127 



Glycerine (pure) 1 ounce. 



Alcohol 2 drachms. 



Water 6 drachms. 



Mix the carmine with a few drops of water, and when well incor- 

 porated add about five drops of liquor ammonia. To this dark- 

 red solution about half an ounce of the glycerine is to be added, 

 and the whole well shaken in a bottle. Next, very gradually pour 

 in the acid glycerine, frequently shaking the bottle during admix- 

 ture. Test the mixture with blue litmus-paper, and if not of a 

 very decidedly acid reaction, a few more drops of acid may be 

 added to the remainder of the glycerine and mixed as before. 

 Lastly, mix the alcohol and water very gradually, shaking the 

 bottle thoroughly after adding each successive portion till the 

 whole is mixed. This fluid may be kept ready prepared, and injec- 

 tions made very rapidly with it. 



33. The method of making injections with these colours is the 

 same as with the gelatine mixtures before described, except that 

 no heat is required, and consequently most of the trouble re- 

 moved. The bottle of the fluid must be well shaken immediately 

 before use ; and when the object is injected, we must allow it to 

 remain in a cool place for a few hours before cutting it. Thin 

 sections of the subject may be cut with Valentin's knife, as 

 before described, and are very beautiful transparent objects. 

 Some of the finer tissues, also, are shown much better by this 

 mode of injection than by the opaque, and are easily mounted by 

 washing in clean water when first separated, and floating upon a 

 slide, where they must be allowed to dry thoroughly. They may 

 then be immediately mounted in balsam, or kept in the dry state 

 until it is convenient to finish them ; but in many cases this keep- 

 ing, if too much prolonged, will injure the object. If it is desired 

 to transfer the section to another slide, it will be necessary to wet 

 it thoroughly with water. by the aid of a camel-hair pencil, and 

 then gently strip it off with the forceps. When it is wished to 

 preserve injected subjects in "masses," it must be done by im- 

 mersion in spirit, and the sections may be cut at leisure. Most 

 of these transparent objects may be mounted in Canada balsam ; 

 but some recommend glycerine or glycerine jelly, as allowing the 



