METHODS. 5 



vaselin may be varied somewhat to suit the object ; a 

 softer mixture is produced by increasing the proportion 

 of vaselin. For soft objects cacao-butter, which has 

 the advantage of being soluble in ether or chloroform, 

 is useful. 



The method of imbedding is to make a cavity in a 

 piece of the substance sufficiently large to contain the 

 object, which must have been previously washed with 

 alcohol to remove all traces of water from its surface ; 

 a small quantity of the substance is then melted and 

 poured into the cavity so as to surround and cover the 

 object. When it is cold it may be cut. 



Another method of imbedding is to moisten the 

 object in water, and then suspend it by means of a pin 

 attached to a thread in some white of egg, which has 

 been previously well shaken up, and then strained 

 through muslin. The white of egg should be in an 

 evaporating dish. The object should be left thus sus- 

 pended for some hours, so that the white of egg may 

 come into close contact with all parts of it. Heat is 

 then applied by means of a water-bath, and the white 

 of egg coagulates. The part surrounding the object is 

 now cut out and hardened in alcohol for some days. 

 This method is useful for making sections of buds and 

 flowers. 



It is important to keep the imbedded objects wet 

 with alcohol during the process of cutting, in order to 

 prevent the drying-up of the object, and its consequent 

 contraction away from the substance in which it is 

 imbedded. 



A third method of imbedding is very useful when it 

 is desired to obtain sections of very small objects, such 



