MOUNTING AND PREPARATION OF OBJECTS. 65 



cerine, and kept in the dark when not under ex- 

 amination. 



The majority of pathological products require to 

 be cut into thin sections, before their examination is 

 possible. For this purpose they are placed while 

 fresh in Muller's fluid, which consists of: 



Bichromate of Potash, 2 parts. 

 Sodium Sulphate, 1 part. 

 Water, 100 parts. 



This should be omitted if the sections require 

 staining with chloride of gold, or nitrate of silver. 



The organ or tissue is cut into sufficiently small 

 pieces, and placed for three hours in a very thick 

 solution of gum. A little alcohol added to the gum 

 prevents putrefaction and allows it to be used for a 

 considerable time. 



The instruments required for section cutting, are a 

 razor and a microtome. The razor is set in a strong 

 wooden handle, it should have a good thick back, 

 loth sides being hollow ground. 



Rutherford's microtome consists of a brass table, 

 in which a cylinder containing a piston is inserted. 

 The piston can be raised or lowered by a fine 

 threaded screw. A box covered with gutta percha 

 and projecting beyond the table, surrounds the cy- 

 linder ; in its bottom is a drainage tube to carry off 

 the melted ice and salt. 



Several modifications of Rutherford's microtome 

 have been lately introduced, every one of which is 

 greatly inferior to the original, the worst form being 



