RECIPES, FORMULA AND USEFUL HINTS. 139 



Soak the gelatine over night in water; in the morning add the 

 swelled gelatine to the glycerine and carbolic acid heated to about 200 

 Fahr. in a water bath. Continue the heating several hours until the 

 water is all expelled. Then filter and bottle. The filtering is difficult 

 and can only be accomplished by the aid of heat. 



Glycerine jelly. 



The original method of making this is as follows : Take any quan- 

 tity of gelatine and let it soak several hours in cold water. Pour off 

 the superfluous water and melt the soaked gelatine by the aid of heat. 

 To each ounce of the fluid gelatine add one drachm of alcohol and 

 mix well. Then add a fluid drachm of the white of an egg and mix 

 well while the gelatine is cool but still fluid. Now boil until the albu- 

 men coagulates and the gelatine is quite clear. Filter through fine 

 flannel, and to each fluid ounce of the clarified gelatine add six fluid 

 drachms of pure glycerine (Price's is the best) and mix well. 



Glycerine and gum. 



Dissolve two parts by weight of gum arabic in two parts of cold water 

 and add one part of glycerine. Mix well but use no heat, and strain. 

 Keep in a tightly stoppered vial. This medium has the advantage in 

 mounting, that no heat is required, while it becomes solid in a short 

 time after mounting. 



Dr. Lang's method of studying nervous histology of the Turbel- 

 laria. 



50 parts I per cent, solution of Picrocarminate of ammonia. 



50 parts 2 per cent, aqueous solution of eosin. 



Objects are hardened in alcohol and placed in this solution one-half 

 to four days. The picric acid is then extracted by 70 per cent, alcohol, 

 and the specimens washed with 90 per cent, and absolute alcohol as long 

 as any eosin is dissolved. In embedding in paraffine a copious use of 

 creasote is recommended. This produces in sections of Dendrocoela, 

 carmine red nuclei and nucleoli, glands, adipose tissue, while all other 

 parts are eosin red. 



Dr. Treub, in studying the nuclei of plants, first killed the cells by 



