136 
METHODS IN PLANT HISTOLOGY 
Miss Langdon cleared 15-mm. cubes of Dioon stem in a similar 
way, but used equal parts of xylol and carbon disulphide instead of 
cedar oil. The course of the bundles could be traced perfectly, 
Fig. 26 .—Sphenophyllum pleurifoliatum: transverse section of a stem, cut from a coal ball 
of the Upper Carboniferous. Eastman Commercial Ortho film, Wratten E (orange) filter, J. 
Swift and Son 1-inch lens; arc light; exposure, 1 second. Slide by Lomax, negative by Sedgwick. 
X19. 
