CHAPTER XII 
SPECIAL METHODS 
In the preceding chapters it has been our object to present the 
principal methods of preparing plant material for microscopic 
examination in such a way that good preparations may be obtained 
as soon as possible. The schedules afford an easy introduction to the 
various methods, but it is hoped that the methods have been so 
presented that the student has become grounded in the fundamentals, 
because some modification is likely to be necessary in nearly every 
piece of research. A few methods designed to meet special difficulties 
are given in this chapter and others are mentioned in the second 
part of the book, in connection with various laboratory types. 
VERY LARGE SECTIONS 
It is sometimes desirable to cut very large sections. Sections 
as large as a cornstalk may be cut freehand or in celloidin. A section 
of a stem of Zamia 5 or 6 cm. in diameter is difficult to handle by the 
usual methods. If a large microtome, such as is used in cutting 
complete sections of large brains, is available, the piece of stem is 
easily held for the cutting. Some of the medium-sized sliding 
microtomes now have a rigid clamp which will grip a block 3 cm. 
square. The lower part of the piece can then be trimmed to fit the 
clamp, leaving the upper part round, so that sections across a stem 
6 or 7 cm. in diameter may be cut without much difficulty. With a 
rather soft stem, like Zamia , the surface must be flooded with 95 per 
cent alcohol after each section, if it is desirable to cut thin sections. 
From stems 3 cm. in diameter, sections can be cut at about 20 to 
30 ji. If the section is not more than 3 or 4 cm in diameter, it can 
be mounted on a 50X75 mm. slide. Sections 6 or 7 cm. in diameter 
can be mounted on lantern slides; if large covers are not available, 
use another lantern slide for a cover. It will be easier to get neat 
mounts if the cover is cut down so as to leave a margin 2 or 3 mm. 
wide. It is not easy to mount a thick section between 2 lantern 
slides of the same size, on account of the balsam which oozes out at 
132 
