368 APPENDIX. 



37° C, and thus serves as an indication of the 

 limit of temperature that can be used in the 

 observation without injury. 



FarafSin B. 



Paraffin 2 parts. 



Vaseline 1 part. 

 This is one of the best imbedding mixtures for general 

 purposes, it can be made harder by adding a little 

 more paraffin. 



Spermaceti and Castor oil. 



Spermaceti 40 grms. 

 Castor oil 10 grms. 



Section cutting. 



In order to make thin sections it is absolutely necessary 

 to have a sharp razor. It sometimes happens that a 

 student who has resigned himself to the belief that 

 he cannot cut thin sections finds no difficulty in 

 doing so on buying a new razor. 



In carrying on a class, where it is required to cut a 

 considerable number of equally good sections, a 

 microtome is almost indispensable; perhaps the 

 most useful for a Demonstrator's purpose is the 

 freezing microtome made by Swift, Optician, Totten- 

 ham Court Boad, London. The one in which 

 ice and salt is used, is recommended in preference 

 to the one in which ether is used, since it is less 

 liable to get out of order, and when once started 

 will continue freezing for two to three and a half 

 hours. Equal parts of ice and salt are taken, and 

 pounded up together in a mortar, then packed 

 tightly in the box of the microtome. 



