Study of Wood Structure. 575 



writings of earlier authors, as above mentioned. When the stu- 

 dent takes up another author he is obHged to spend a good deal 

 of his time in learning the different names the author uses. Un- 

 fortunately writers on wood structure do not hold themselves 

 bound to employ a recognized set of terms, but they feel them- 

 selves privileged to invent terms unfamiliar to a large body of 

 readers. 



One unfamiliar with the results of investigations published be- 

 tween the years 1800 and i860 can not appreciate the hopeless 

 confusion met with, and it is very difficult for a student to master 

 all the terms used during that time. Any student, and particu- 

 larly the young student, considers the name of an element he once 

 learned to be a part of that element, and it is not until his mind 

 is mature when he sees a certain structure exactly alike under 

 three or more different names. Give a student the name trachea 

 for a tracheid, which is what some writers are doing, he will 

 naturally change his notion of one or both of these elements. 



This chaotic condition of nomenclature was thought to be prac- 

 tically settled when Sanio in 1863 published his work entitled 

 "Vergleichende Untersuchungen iiber die Elementarorgane des 

 Holzkorpers." Although he had his opponents, the majority of 

 writers and investigators followed him, and even to-day there 

 are a number of investigators who do not propose to accept any 

 other nomenclature and classification. Since 1863 a great many 

 discoveries were made, and Sanio's terminology of necessity suf- 

 fered changes to a certain extent, especially in as far as the gen- 

 eral grouping of the elements is concerned. For example, the 

 elements of the pith rays can not be classed with the wood- 

 parenchyma fibers. The pith-ray cells are a slight modification 

 of primary tissue, while wood-parenchyma fibers are elements 

 that may be classed more appropriately with wood fibers and 

 tracheids (wood prosenchyma) . The following are lists of 

 names used for the same elements : 



Vessels. — Other names in use : tracheae, ducts, tubes, pores, 

 fistulae, vasa, and wood-vessels. 



Tracheids. — Other names in use : tracheae, fibrous elements, 

 wood fibers, and vascular fibers. 



Wood Hhers. — Other names in use: libriform fibers or cells, 

 fibrous cells, fibrous elements, xylem elements, woody fibers, pro- 

 senchyma fibers, and wood prosenchyma. 



