496 APPENDIX. 



F. SECTIONS AND SECTION CUTTING. 



Directions for preparing sections of the vegetable tissues will 

 be found incorporated in the text; those which follow apply to 

 the animal series alone. 



1. Imbedding. 



All tissues or embryos about to be imbedded, whether 

 stained or unstained, should have been first well hardened 

 in 90 p. c. alcohol. 



For imbedding, a mixture of hard and soft paraffins is 

 most serviceable, such as shall melt at from 50'' to 6o^ 



The preparation to be imbedded, if stained, should be 

 first soaked in turpentine to saturation ; if unstained, it 

 may be transferred direct from the alcohol. In either 

 case it must be placed in melted paraffin (the temperature 

 of which must not exceed that of its melting point) until 

 thoroughly permeated thereby. When ready for imbed- 

 ding, take of the solid paraffin a piece of about the 

 calibre of a candle and excavate at one end a pit, large 

 enough to fully accommodate the preparation ; then 

 transfer the latter and fill the pit with melted paraffin. 

 Put the whole aside, until quite cool and firmly set. 



2. Cutting. 



For this purpose an ordinary razor will suffice, so far as 

 the requirements of this volume are concerned. The 

 edge should be kept permanently sharp. 



Before cutting, pare away the imbedding material, so 

 as to reduce that which surrounds the preparation to the 

 minimum. 



J- 



Mounting. 



Transfer the sections as cut, paraffin and all, to micro- 

 scopic slides previously prepared by one of the two 

 undermentioned methods, and proceed as directed in 

 either case. 



