Collecting and Subdividing Plant Materials 7 1 



at once for further trimming. Split a disk radially into pieces having 

 uninjmed blocks of bark firmly attached to the wood. Trim off 

 enough of the inner part of the wedge of wood to leave a block of 

 sapwood with several annual rings and with cambium and all outer 

 tissues intact (Fig. 2.2 D-F) . With a razor blade split a thin layer 

 from the two radial faces, from the inner tangential surface and from 

 the transverse faces of the block, thereby removing tissues that were 

 compressed during the preliminary trimming. Keep the material wet 

 during these operations. Drop the pieces into the killing Huid at 

 once after final trimming. 



Wood from dead logs, dry lumber, or furniture wood requires 

 proper trimming to establish the future cutting planes. It is usually 

 easy to establish the radial plane by splitting the wood longitudinally, 

 parallel to a ray. At right angles to this plane, split the block longi- 

 tudinally along the tangential plane, and then trim in the third 

 or transverse plane. Rough splitting can be done best with a plane 

 bit, and rough crosscutting with a fine-toothed high-speed mechanical 

 saw. Finally, trim all faces with a razor blade to remove surface tissues 

 that were damaged by the rough trimming. Subsequent processing 

 of the wood is described in the section on the preparation of hard 

 tissues. 



The handling of more specialized and difficult materials such as 

 buds, floral organs, and fruits is described to better advantage in 

 Part II in conjunction with detailed directions for processing such 

 materials. The handling of plant bodies and organs of the lower 

 phyla is also described in Part II. 



The foregoing brief outline of methods of collecting and prepar- 

 ing material for preservation can be modified and adapted to meet 

 most problems. The principal preliminary operations and precautions 

 necessary for successful processing may be summarized as follows: 



1. Use fresh, normal material. 



2. Remove pieces having the desired features and oriented so as 

 to establish planes in which microtome sections are to be cut. 



3. Cut into suitable pieces, with minimum bruising, compression, 

 or desiccation. 



4. Immerse the pieces promptly into the killing (fixing) fluid 

 (Chap. 3) , and promote quick penetration of the fluid by removing 



air with an aspirator (Fig. 3.1) . 



5. Record the necessary data concerning species, location, date, 

 parts selected, and killing fluid used. 



