14 MICRO-CHEMICAL REAGENTS. 



AMMONIA. 



A concentrated solution of ammonia in water is 

 often used instead of potash, where the latter 

 would act too powerfully. 1 We have also men- 

 tioned its use in clearing tissues by Hanstein's 

 method. 



As a test for protein combinations, including 

 crystalloids, it is employed with nitric acid to in- 

 tensify the color of the xantho-protein reaction. 

 When a thin section of a tissue composed of cells 

 with thickened walls is successively treated with 

 nitric acid and ammonia, the middle lamella (inter- 

 cellular substance) is colored yellow. 2 



Finally, it is employed in the preparation of 

 cupro-sulphate and carminate of ammonia. 3 



Ammonia is also valuable for restoring the form 

 of herbarium specimens of phaenogams, algae, and 

 mosses, as well as spores, pollen grains, etc., that 

 are to be examined microscopically. 



CUPRAMMONIA (Cuoxam, Cramer; Cupridiamin). 



This important reagent must be freshly made 

 when needed for use, as it deteriorates with age. 

 When it is desirable to keep it for a time it should 

 be set in the dark. 



1 Dippel: Das Mikroskop, I., p. 279. Weiss: Allgem. Bot., 1878, 

 pp. 77. 144. 



2 Dippel : Das Mikroskop, II., p. 100. 

 8 See the section on staining agents. 



