Methods for Embedding and Cutting 



Sections. 



Free Hand Cutting. 



It is usually necessary to surround the tissues to 

 be cut with some material, which gives no resistance to, 

 and does not injure the knife, at the same time is firm 

 enough to give support. Pathologists have for a long 

 time used small strips of amyloid liver which had been 

 hardened in alcohol or Miiller's fluid. If these can not 

 be obtained, pig's or calf's liver will answer. Elder- 

 pith is also used. The little blocks of liver tissue, or the 

 elder-pith rods, are divided into two parts, between which 

 the tissue to be cut is placed. It can now be firmly 

 held between the thumb and the index finger of the left 

 hand. A razor, which is fiat on one side (the under while 

 in use), is employed. Its upi)er surface is well covered 

 with 80% alcohol. Try to make the section with one con- 

 tinuous cut, resting the blade of the knife on the index 

 finger. Sections which answer for purposes of orientation 

 can easily be m:ide in this way. They are, however, not to 

 be compared with the ones that can be cut with the 

 microtome when the tissues are properly embedded. 



Embedding Tissues. 



A great man}' methods for embedding tissues are in 

 use, the principle involved is the same in all. In the one 

 case the tissues are permeated with substances that are 

 fluid when warm and become hard enough to cut on cool- 

 ing; in others again, the embedding mass hardens, on the 

 evaporation of a solvent which was used to bring them to a 

 fluid state. The methods for embedding in celloidin, in 



