4 ANATOMY OF THE GYMNOSPERMS 



studies brought forth facts which gave repeated emphasis of the 

 most positive kind to the idea that questions of phylogeny cannot 

 be settled either by the morphologist in the narrower sense or 

 by the physiologist when acting independently, and that a proper 

 historical point of view can be gained only when to such labors 

 we join the data derived from a critical study of the stem structure 

 in all its details. 



The original intention was to make a complete study of all the 

 North American woods, comprising, as enumerated by Sargent 

 in his report in the Tenth Census of the United States, some four 

 hundred and nineteen species and varieties ; but the great impor- 

 tance of the Coniferae from an economic point of view, their fre- 

 quent representation in the fossil state, and their relatively more 

 simple structure eventually led to their selection as the one group 

 in which initial studies might be prosecuted with the most imme- 

 diate and profitable results. While the North American species 

 constituted the original basis, various exotic species were added 

 from time to time, with the result that our studies, as now com- 

 pleted, comprise ninety-two species from North America, twenty- 

 one species from Japan, and four species from Australasia. This 

 extension has proved of great value, not only from a paleonto- 

 logical point of view but also because of the important bearing 

 such exotic types have had in the solution of questions relating 

 to descent. 



In determining the particular nature of the material to be dealt 

 with in the prosecution of these studies several considerations 

 of fundamental importance were kept in mind, among the more 

 prominent of which we may consider the following. 



The economic application of wood involves the employment, 

 solely, of the material which lies within the woody zone between 

 the bark and the pith. It was therefore held that for the recogni- 

 tion of timber or wood derived from constructions of any kind that 

 these two latter regions of the stem would be worthless, and that 

 a system should be devised which would, if possible, permit the 

 recognition of the species apart from such structures. Experience 

 has not only shown that this is possible, but that the characters 



