Journal of Applied Microscopy. 461 



The Preparation and Mounting of Wood Sections. 



I commence this paper with the full realization that, by tli-e side of highly 

 specialized laboratory methods, I am writing in a very humble sphere, but I 

 offer no apology. It is to be remembered that there is a great deal of valuable 

 microscopical study that is not done in laboratories, and by those who have not 

 the time or means for elaborate methods, nor is it to be forgotten that well pre- 

 pared vegetable sections hold a large place in educational work. 



The first thing required for successful section-cutting is a good microtome ; 

 no matter how cheap, or by whom made, so long as it does its work well. It is 

 not every one that can train his nerves and muscles to cut free-hand sections of 

 any size and uniformity of thickness. Good section-cutting means a knife of the 

 finest steel, and the finest edge ; the wake of " saw teeth " in an imperfectly 

 sharpened knife never looks well in a wood section, and this sharpening of a 

 knife is something that does not come of itself, it requires practice. No edge 

 thin enough for fine sectioning will stand hard wood, unsoftened, and I have 

 found nothing quite as good for this purpose as boiling for a short time, or soak- 

 ing for two or three days in a strong solution of pearline ; it softens without 

 destroying any part of the tissue. 



For imbedding use hard paraffin, especially in the summer; it shrinks less, 

 holds the object more firmly, and the edges of material imbedded are less likely 

 to tear. If the paraffin rolls, as it most likely will, press it lightly with the ball 

 of the finger as the knife goes through it — no danger of sectioning the finger. 



Next in importance is the right thickness of the section, which should be 

 governed entirely by the object to be attained by observation, and not by the 

 exercise of mechanical genius in cutting as thin as possible. Hard and compact 

 tissue., like most of the woods, requires to be cut very thin, while objects like 

 Pteres aquilina, root or stem, with large fibro-vascular bundles, require to be cut 

 thicker to preserve the structure complete, and the section entire. This holds 

 true especially of longitudinal sections. After cutting a few sections, examine 

 with the microscope and vary the thickness, if necessary, till the desired result is 

 reached ; time spent in this way is time saved. It makes a difference whether the 

 section is to be mounted in balsam, or some other medium, as will be seen 

 hereafter. 



If transparency is desired, most sections require to be bleached before stain- 

 ing. A good rule is to bleach till the chlorophyll disappears, or the color from 

 the wood is discharged, and no longer. If bleached too little, the sections will 

 be disfigured with dark blotches ; if bleached too much, the section will go to 

 pieces, or its character will be destroyed. The bleaching fluid must be well 

 soaked out, in repeated changes of pure water, or staining will be a failure. 



The primary object of staining, single or double, is not for beauty, but for 

 use, and yet a beautiful slide is not to be despised on that account. Slides are 

 educators, and the education of the sense of beauty is no barrier to scientific 

 research, and it is quite possible that in some cases it may be an inspiration. 

 It requires but little skill to so stain a wood section as to bring out stunning 



