504 RECORD OF CURRENT RESEARCHES RELATING TO 



preparation will be sufficiently hardened to allow of the slide being 

 cleaned. For this purpose the parts of the surface of the slide and 

 cover-fflass to which the gelatine adheres should be scraped off with 

 a knife, and rubbed over with fine powdered chalk by an ordinary 

 brush, and then cleaned with a dry rag." 



Dr. E. Kaiser also describes * a process for preparing a chemically 

 and " microscopically " pure glycerine-gelatine as follows : — One part 

 by weight of the finest French gelatine is left for about two hours in 

 six parts by weight of distilled water, seven parts of chemically pure 

 glycerine are added, and for every 100 grams of the mixture 1 gram 

 of concentrated carbolic acid. The whole is warmed for ten to fifteen 

 minutes, stirring all the while until the whole of the flakes produced 

 by the carbolic acid have disappeared. Finally, it is filtered while 

 still warm through the finest spun glass which has been previously 

 washed in distilled water and laid whilst still wet in the filter. 

 When cold the preparation may be used like Canada balsam. 



Glycerine-Gelatine as an Embedding Substance. — Dr. Kaiser in 

 the same paper points out that the above forms also an excellent 

 embedding substance for making sections. For this purpose the 

 objects are placed in the glycerine-gelatine after it has been again 

 warmed. When sections of objects have to be made so delicate that 

 there is danger of their falling to pieces after being cut, 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 embedding harder objects glycerine-gelatine is an excellent 

 medium, for after it is set, any degree of hai-dness may be imparted to 

 it by treating it with absolute alcohol, the time required for this being 

 from ten to thirty minutes. 



A special recommendation of this substance for embedding is 

 its transparency, which enables the operator to see at any moment 

 what the position of the object is. 



Brandt's Microtome.'!'— Herr Brandt has devised a modification 

 of the Kivet microtome (in wood). The body of the microtome is cut 

 through the middle longitudinally, and the two halves movably 

 attached behind by a hinge, so that they can be made to diverge at any 

 angle, and be fixed by means of a clamping screw in any position. By 

 this arrangement the idea suggested and carried out by Dr. Long, of 

 Breslau, of making the right and left grooves not parallel but diverging 

 towards the front, is still further extended, as it lies in the power of 

 the operator to increase the angle of divergence at pleasure, and make 

 the knife take a greater or less lateral motion. Herr Brandt has suc- 

 ceeded by this means in making- good sections of objects of most 

 delicate structure which he failed to do to such perfection in any other 

 way. 



* ' Bot. Ceulralb.,' i. (1880) p. 25. 



t ' Zeitsclir. f. Mikr.,' ii. (ISyO) p. 172. 



