128 BROWN: Woops FOR MICROSCOPIC STUDY 
tissues of the woods of temperate regions, to which anatomical 
work has, in large part, been confined. Such tissues often cut 
satisfactorily without treatment, while even oak and hickory, 
among the hardest of such woods, if taken from fresh (green) 
material, may be satisfactorily sectioned along any plane, by a 
microtome, without any preparatory treatment. Tropical wood 
collections, on the other hand, ordinarily embrace a high proportion 
of species the tissues of which, particularly when selected from 
dry material, can only be cut after a more or less prolonged treat- 
ment, the nature of which varies considerably according to the 
structural features of the species or type. Moreover, after sections 
of sufficient clearness have been obtained, to an even greater 
degree than in temperate woods, there are many anatomical 
characters, often of the greatest interest, which cannot be satis- 
factorily observed without the use of reagents, stains, or media of 
definite refractive properties. To meet the particular needs in 
this field, there is insufficient information at hand, and, further, 
little seems to have been added in recent years. Papers marking 
distinct progress in anatomical work too often neglect to publish 
essential details in the methods employed. 
During the years 1916-1918, the writer carried out an extended 
investigation of the woods of Hawaii. In the course of these 
studies it was found necessary to devote a very considerable 
amount of the time to the preparation of slides, and altogether 
more than three thousand permanent mounts were made, including 
approximately one hundred macerations. In connection with 
this work, various accepted methods were tested and a number 
of new ones were devised. In the present paper, the technique 
employed is described in some detail, particular attention 
being called to certain heretofore undescribed methods of treat- 
ment and to a number of improvements on the methods in 
in common use. While emphasis is thus placed upon the treat- 
ment of the highly complex woody tissues of tropical dicotyledons, 
the suggestions embodied should be of value in the treatment of 
other woods than tropical, or of other than woody tissues, in that, 
to a certain extent, the treatment of some of the cellulose tissues 
of the stem, particularly the collenchyma and phloem layers, has 
been included. 
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