32 MICRO-CHEMICAL REAGENTS. 



has the power of dissolving crystalloids, at least in 

 the embryo of Bertholletia. 1 



CHLORIDE OF CALCIUM. 



In an aqueous solution (two to three parts of 

 water to one of the salt) this substance is some- 

 times used as a mounting medium for permanent 

 preparations excepting those which contain amy- 

 lum, although for this purpose glycerine has largely 

 replaced it. Recently it has found application for 

 clearing tissues. The section which is to be treated 

 is placed in a few drops of water and sprinkled with 

 the dry pulverized salt. It is then warmed over a 

 gentle flame until nearly dry, and again moistened 

 with a few drops of water, after which it is laid in 

 glycerine, where, in the course of a few hours, it 

 acquires a very satisfactory degree of transparency. 

 (Treub's method. 2 ) 



CHLORIDE OF MERCURY (Corrosive Sublimate). 



A very dilute aqueous solution (1:100) is used to 

 make the finest protoplasmic currents evident. 3 



1 Weyl : Zeitschr. fur phys. Chemie, Bd. I., p. 90. 



2 Treub: Meristeme primitif de la racine. Muse"e de Leyde, 1876, 

 Tome II., p. 9. Eriksson : Meristemet i dicotyla vaxters rotter, p. 10. 

 Flahault : Accroissement terminale de la racine. Ann. des Sc. Nat., Bot., 

 1878, p. 24. 



3 Dippel : Das Mikroskop I., p. 281. 



