264 PHOTOMICROGRAPHY 



FLEMMING'S FLUID (Chromo-aceto-osmic Acid). 



Chromic acid 1 % solution 25 parts 



Osmic acid 1% 10 



Acetic acid 1% 10 



Water 55 



This is a cheaper fluid than Hermann's, but equally useful. 

 Neither of these fluids penetrates very well, consequently 



the tissues to be fixed should be cut into very small pieces. 



Objects may remain in these fluids for several hours or even 



days ; they are afterwards washed in running water for 6 



hours and passed through graded alcohols. 



ACETIC ALCOHOL. 



Absolute alcohol 6 parts 



Glacial acetic acid 1 part 



Chloroform 3 parts 



This is very useful in such cases as the segmenting eggs of 

 Ascaris, which are covered with a shell that resists the passage 

 of fixing fluids such as Hermann's or Flemming's. 



After fixing, the objects are washed in strong alcohol (95%) 

 until all traces of smell of acetic acid have disappeared. 



STAINING REAGENTS 



BORAX-CARMINE (Grenacher). 



To a 4% solution of borax in water add 3% of carmine and 

 boil, to this add an equal quantity of 70% alcohol, leave 

 standing for 2 days and filter. 



Objects to be stained in bulk should be left in the stain 

 until thoroughly penetrated, from 2 hours to several days, 

 according to size. They are then placed in acid alcohol 

 (alcohol 70% 100 c.c., hydrochloric acid 4 drops) and left in 

 this until they have a bright red translucent appearance, they 

 are then washed in 70% alcohol to remove all traces of acid. 



For staining sections this fluid is not so satisfactory as 

 Carmalum. 



CARMALUM (Mayer). 



Carminic acid 1 gram. 



Alum 10 ,, 



Hot distilled water 200 c.c. 



To the solution add a few drops of thymol as a preservative. 

 The material after staining must be washed in water prior to 

 placing in alcohol, otherwise crystals of alum are liable to be 

 deposited. 



