ii 4 ELEMENTARY TECHNOLOGY. 



or the electrical stage are all useful in observing living tissues. 

 2. Hardening tissues. 



Hardening tissues which are too soft to be cut or dissected. 



Chromic acid in dilute solution of pale lemon color. Small 

 pieces of tissue y 2 inch square, in large quantities of solution 

 from two days to two months. 



Picric acid. Saturated solution in cold water. 



Mutter's fluid. Potassium bichromate 2.5 grammes, sodium 

 sulphate I gramme, dist. water 100 C C. Very generally use- 

 ful. 



Potass, bichromate. One or 2 per cent solution. For blood 

 corpuscles .even 50 per cent. 



Alcohol. For rapid hardening. At first weak, then strong, 

 then absolute. Chiefly used to complete hardening after 

 chromic acid, etc. 



Chromic acid and alcohol. Chromic acid I gramme, water 

 20 C C, dissolve and add slowly alcohol 180 C C. Useful for 

 delicate tissues, as retina, cochlea, etc. 



Osmic acid, i-io to I per cent solution hardens embry- 

 onic and nerve fibers. 



Freezing. For quickly hardening and cutting fresh tissues 

 not needed for preservation, or for completing for section par- 

 tially hardened tissues. 



j. Softening hard tissues. 



1 . Removal of calcareous matter, as from bone or teeth. 

 Chromic and nitric acid. Chromic acid I gramme, water 



200 C C. Dissolve and add commercial nitric acid 2 C C. A 

 y 2 per cent solution of chromic acid or a strong solution of 

 picric acid may also be used. 



2. Softening connective tissues. 



Dilute alcohol. One part to 2 of water. Softens white 

 fibrous tissue, as in separating muscle fibers or epithelial cells. 



Dilute sulphuric acid i to I ooo. 



Acetic acid arid glycerine. One oz. glycerine and 5 drops 

 glacial acetic acid is recommended by Beale for softening 

 white fibrous tissue and tracing nerve fibers with high powers- 

 ^. Mechanical separation of tissue elements. 



