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1910] BRIEFER ARTICLES 57 
at Beaufort, N. C. I am indebted to Hon. Georcr M. Bowers, U. S. 
Fish Commissioner, for the privilege of working in this laboratory, and 
to the director, Mr. Henry D. ALLER, for many courtesies extended to 
me during this investigation. 
Summary 
Plants of Dictyota dichotoma raised from fertilized eggs gave 33 tetra- 
sporic plants and no sexual ones. Plants raised from tetraspores gave 
64 sexual plants and no tetrasporic ones. 
The tetraspores of a single plant produced both male and female 
plants, in one case in about equal numbers.—W. D. Hoyt, The Johns 
Hopkins U niversity, 
MICROTECHNIQUE FOR WOODY STRUCTURES 
In the preparation of thin sections (5 » or less) of hard tissues the cel- 
loidin method has been largely used with excellent results. The method 
as originally described by PLowmAn7 has been modified during the last 
few years at the laboratories of plant morphology of Harvard University, 
to meet the demands of work with special classes of hard tissues. 
In reply to numerous inquiries as to the best method of preparing thin 
sections of woody tissues (trees and shrubs), and as to the advisability of 
using the celloidin technique, the following methods of treatment used in 
Preparing slides for photomicrography, the study of wood structure, and 
struction in wood technology are described. 
1. SELECTION OF MATERIAL.—In working with old and thoroughly 
dried material, the blocks for treatment should be cut from the interior 
of the piece and as far from the finely checked outer surface as possible. 
Green material and sapwood are often preferable in working with the woods 
of SymMnosperms, especially with the pines, in order to prevent shredding 
of the transverse sections and tearing-out of the resin canals. The blocks 
Should be cut in such a manner that the faces represent sections which are 
as nearly transverse, radial, and tangential as possible. In working with 
soft woods, larger blocks may be used to advantage than with hard woods, 
and in the case of extremely hard woods the transverse face particularly 
Must be trimmed down to small dimensions. : 
2. BoILInc.—The blocks should be given a very thorough boiling in 
Water to drive out the air and allow the hydrofluoric acid, used in the next 
Step of the process, to penetrate to all parts of the wood. Repeated boilings 
and additions of cold water hasten the process of driving out the air. 
”PLowman, A. B., The celloidin method with hard tissues. Bot. GazeTre 
372456-46r, 1904. 
