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XXXIV. 



MAHOGANY, AND THE RECOGNITION OF SOME OF THE 

 DIFFERENT KINDS BY THEIR MICROSCOPIC CHARACTERISTICS. 



By HENRY H. DIXON, Sc.D., F.R.S., 

 University Professor of Botany, Trinity College, Dublin. 



(Plates XXII.-XLIV.) 



[Read Apuil 23 ; published Decemhkk 7, 1918.1 



Definition of Mahogany. 



As a rule the general or trade names of timbers are applied to the woods 

 yielded by one species, or at most by one genus, of tree. Even with this 

 limitation it is found that often the physical properties of the timber, 

 designated by any one name, may be inconveniently variable, depending as 

 they do in part on the conditions under which the tree has grown. This 

 variability of physical characters is often associated with variations in 

 structure, or variations of structure which do not involve other physical 

 differences may occur, so that accurate description and identification are 

 rendered difficult. 



In the case of mahogany, however, no such limitations have been observed, 

 and the mahogany of commerce is well known to be derived from many 

 different genera and species of trees. Furthermore, as we might expect, in 

 these cases, too, the varying conditions under which the different trees grow 

 impose many modifications on the properties of their timbers, and conse- 

 quently there is extreme latitude for variety of appearance, of physical 

 properties, and of minute structure in the woods classed as mahoganies. 



Some idea of the number of woods connoted by this name may be obtaiiied 

 from C. D. Mell's paper (10), where he lists some sixty-seven species of trees 

 as supplying timbers whose characteristics sufficiently coincide with the 

 popular idea of mahogany to be marketed as that wood. It is certain that his 

 list might be added to from our present knowledge, and may well be further 

 largely increased as the properties of unexamined timbers are ascertained.. In 

 this present piece of work, which must be regarded as only preliminary, I 

 have had the opportunity of examining the wood of only about forty species 

 of trees which yield mahogany. 



Only in a few cases has it been possible to obtain reliable records of the 

 identification of the tree supplying the timber; usually in commercial samples 



SOIENT, PROC. K.D.S., VOL XV., NO. XXXIV, 3 3 





