350 



APPENDIX. 



having been roughly smoothed with a plane or chisel, a shaving can 

 be easily cut with a well-sharpened plane which, though not equally 

 thin all over, will serve all the purposes of study. It is best to drop 

 the shaving at once into some liquid dye, such as an alcoholic solution 

 of methyl violet, as this renders the structure far more readily visible 

 under the microscope. After dyeing, the thinner part of the shaving 

 can be cut square with scissors and mounted, for which purpose we 

 personally prefer an extra wide glass slip and a square cover-glass. 

 If carefully dried under moderate pressure the sections can be 

 preserved unmounted or mounted on paper, like the series prepared 

 by Herr Nordlinger. 



Another method we have found efficacious is to immerse a small 

 squared specimen in a basin of water, such as a deep photographic 

 basin, by means of metal weights, and then to slice off thin shavings 

 with a broad chisel. The sections floating to the surface may then be 

 dyed, or may be simply floated on to slips of glass, lightly covered 

 with thin cover-slips and then dried slowly and cemented down. It 

 is important to use thin cover-slips. 



Though the transverse section is most important, longitudinal ones, 

 either radial or tangential, are often also of use, the latter, for 

 instance, affording the readiest means of distinguishing Alder from 

 Birch. 



: flYiL 



I, 01 C. 

 AVIATION LPABY 



