WHITE OF EGG CONGELATION MASS. 171 



glycerin ; a cover is put on, and the mount closed with any 

 suitable cement. In process of time the glycerin will permeate 

 the gelatin and convert it into glycerin jelly ; this may be 

 hastened by placing the slide in an oven kept at about 20 to 

 30 C. 



311. Gum- Gelatin Congelation Mass (JACOBS, Amer. Natural., 

 1885, p. 734; Journ. Eoy. Hie. floe., 1885, p. 900). Gum 

 arabic, 5 parts ; gum tragacanth, 1 part ; gelatin, 1 part. 

 Dissolve in enough warm water (containing one sixth of 

 glycerin) to give a mass of the consistency of thin jelly when 

 cold. 



312. White of Egg Congelation Mass (KOLLETT, Denkschr. math, 

 naturw. Kl k. Acad. Wiss., Wien, 1885; Zeit.f. wiss. Mik., 1886, p. 92). 

 Small portions of tissue brought in the white of a freshly-laid egg on to 

 the freezing stage, frozen, and cut. The knife must be well cooled. 



