300 ENTOMOLOGY. 



At this temperature the preparation remains until it is 

 completely saturated with the gelatine (from 1 to 3 clays), 

 and is then taken out. A piece of hollow pith or several 

 pieces side by side are cut flat upon one side and the 

 preparation laid upon it or them, the gelatine being 

 dropped upon the latter so as to cover the preparation and 

 fix it to the pith. After cooling for a few minutes the 

 whole is placed in absolute alcohol, where it is to remain 

 for a few days, the longer the better, and it is then ready 

 for the microtome. The microtome having been filled with 

 melted wax, the preparation is immersed in it. After 

 cooling, the wax is cut away so that the knife does not 

 come in contact with it in cutting. Before making each 

 section a drop of oil of cloves is applied to the preparation 

 and the subsequent cut is ready for the slide. Mount 

 using dammar or balsam in benzole, or, better, clear 

 balsam. 



Mounting Sections. — The process of mounting is simple. 

 After the slices are arranged on the glass slide, a little balsam 

 or glycerine jelly is placed on the objects, the slide being 

 held over the flame of a candle so as to slightly heat it and 

 drive off the fluids as well as to liquefy the balsam or jelly, 

 and then a thin cover-glass is placed over the object, and a 

 covering of Brunswick black varnish placed with a brush 

 around the edge of the cover-glass, to prevent the penetra- 

 tion of air or leakage of the fluid within, and allowed to 

 dry for a day or two before being used. 



Dr. Kingsley states that one great difficulty in rapidly 

 mounting in glycerine is in fastening the cover-glass 

 firmly. " Various modes of procedure have been described, 

 possibly the best the writer has seen in print being that 

 which employs paraffine. A still better method is to use a 

 very small amount of glycerine, so little in fact that when 

 the cover is applied the margin of the glycerine does not 

 reach the edge of the glass. Then, with a fine brush, balsam 

 or dammar dissolved in benzol is allowed to run in under 

 the edge of the cover-glass, and after becoming hard the 



