220 THE MICROSvOPE. 



adapted for mounting algse, fungi, vegetable and animal 

 tissues, urinary deposits, casts, epithelium, crystals, 

 starch granules, diatomaceas, &c. For certain delicate 

 organisms, as the desmidiaceee, whose plasma may be- 

 affected by too dense a medium, the jelly may be diluted 

 one-quarter or one-third with camphor- water. 



Dr. E. Kaiser describes a process for preparing a 

 pure glycerized gelatine : Take one part by weight of 

 the finest French gelatine, steep for about two hours 

 in six parts by weight of distilled water, and add 

 seven parts of pure glycerine. Then to every 100 

 grams of the mixture 1 gram of concentrated carbolic 

 acid. The whole must be warmed for ten or fifteen 

 minutes, stirring all the while until the flakes produced 

 by the carbolic acid have disappeared. Then filter 

 while still warm through the finest spun glass, pre- 

 viously washed in distilled water. When cold the 

 preparation can be used like Canada balsam. This 

 medium is also an excellent embedding substance for 

 section-making. For this purpose the objects must bo 

 placed in the glycerine-gelatine after again warming. 

 When sections of objects have to be made so delicate 

 that there is danger of their falling to pieces after cut- 

 ting, the object must be left in the warmed glycerine- 

 gelatine until it is thoroughly penetrated by the latter. 

 The gelatine may be removed from the tissues by a 

 fine jet of warm water after the section is made and 

 placed on the slide. For imbedding hard tissues 

 glycerine-gelatine is an excellent medium, for after it 

 is set, any degree of hardness may be imparted to them 

 by treating with absolute alcohol, the time required 

 for this being from ten to thirty minutes. One special 

 recommendation of this substance for imbedding is its- 

 transparency, which enables the operator to see the 

 precise position of the object. 



For mounting numerous minute objects, Half's 

 Carbolic Acid Fluid is a very useful medium; it is 

 more simple, cleanly and rapid than turpentine for 

 insects, small crustaceans, moluscs, &c. The purest 

 crystals of carbolic acid, with just sufficient water 

 added to render them fluid, produces the best 



