12 FB^PARATION AND MOUNTING 



The writer has little or no experience of this plan, he 

 therefore quotes from Frey as follows : 



"The preparation is allowed to freeze (by contact, it is 

 presumed, with a freezing mixture or solution) until it as- 

 sumes a consistency which will pemit fine sections to be 

 made with a cooled razor. The object is more convenient to 

 handle if it is allowed to freeze on a piece of cork. Nerves 

 and muscles have been treated in this manner with good 

 results. Glands (salivary), livers, spleens, the lungs, skin, 

 and the bodies of embryos (see Beale's process for the same 

 in this work), also ganglia, afford excellent appearances. 

 Indifferent (or neutral) media, such as iodine serum, are to 

 be used in examining such sections. Or the preparation may 

 be held in paraffine wax (diluted or not with oil), or tallow, 

 which have been melted, and the object suspended or 

 plunged in them until they cool, and the cooling may be 

 carried further, if needed, by freezing." 



In reference to this subject, Mr. Kesteven informs the 

 author that he has found the paraffine composition more 

 useful for brain than spinal cord. The former can be cut 

 into any angular shape, and be so held steady for slicing ; 

 but the cord, being round, becomes loosened in its setting of 

 wax (or paraffine), and revolves with the pressure of the knife. 

 For either brain or cord he prefers hand- cutting with a very 

 sharp razor, after the manner of Lockhart Clarke (see Mr. 

 Kesteven's paper in St. Bartholomew's Hospital Reports). 

 If many sections are to be made from a brain, machine- 

 cutting saves much time. The razor should have some 

 spirit of wine dropped on it, so as to prevent the secti >ns 

 adhering. The cutting machines are generally graduated 

 {by a screw and index) on the upward movement, so as to 

 enable one to judgfe of the thickness of the section ; but as 

 the brain substance and paraffine are both yielding to a cer- 

 tain extent, the reading must be taken with allowance. 



