PTERIDOPHYTES— FILICALES 305 



material which is to be imbedded should be in pieces not longer than 



1 cm. 



Pteris aquilina is a good form to practice with. For freehand sec- 

 tions, cut as thin as possible, which will probably be 20 n or thicker. 



Yia, 96. — Dicksonia jmnctilobula: photomicrograph of transverse section of rhizome. Fixed in 

 formalin-acetic alcohol, and stained in safranin and light green. Paraffin section 10 m thick. East- 

 man Commercial Ortho film, Wratten E filter (orange) ; arc light; J. Swift and Son 1-inch lens; ex- 

 posure, 1 second. Negative by Dr. P. J. Sedgwick. X'-i'i. 



Put the sections into water, changing several times to wash out as 

 much of the mucilage as possible. From this point, there are rapid and 

 slow methods of arriving at the finished mount. For a very rapid 



