CUTTING ANIMAL SECTIONS. 



193 



Rutherford's microtome is also capable of being used as 

 a freezing instrument, in a manner easily understood by 

 reference to the ac- 

 companying illustra- 

 tion, it being a section 

 of the instrument 

 already figured. 



The freezing box 

 is surrounded with 

 several layers of 

 flannel, and the ma- 

 chine screwed to the 

 table. The plug 

 K being unscrewed, 

 pour methylated spirit 

 into the tube C, oil 

 the sides of the plug, 

 replace it, and depress 

 the screw to the desired extent. Remove all spirit which 

 has come above the plug K, and carefully close the margin 

 with some hog's-lard to pre- 

 vent the spirit reaching the 

 cavity above the plug. 



The embedding fluid is 

 made by soaking five 

 ounces of picked gum 

 arabic in ten ounces of 

 water, and when it has 

 dissolved add two drachms 

 of camphorated spirit and 

 one drachm of glycerine, 

 after which it is to be strained 

 through calico, and kept in a bottle, free from dust. This 

 mixture, when frozen, cuts very much like a Gruyere cheese. 



O 



FIG. 179, 



FIG. 180. 



