VI.— The Leaf. 



B — THE MATURE LEAF. 



Historical (Venation chiefly). 



1828-32. De Candolle and G. Don 



1866. Bentham . 



1. Longitudinal 



2. Oblique . 

 2a. Divergent 



3. Transverse 



1879-84. Mueller 



1 Longitudinal 



2. Oblique 



3. Transverse 



1900. Deane .... 



PAGE. 



357 



358 

 359 

 359 

 360 



361 



362 

 362 

 363 

 364 



65 



(Venation and oil chiefly). 



1899-1900 Gildemeister and Hoffmann .... 367 



1901-2. Baker and Smith 367 



1913. E. C. Andrews ........ 368 



1913 R. H. Cambage 369 



1913 R. T. Baker 370 



191S. Baker and Smith 370 



1920 Baker and Smith 371 



Correlation of the leaf-venation, and chemical constituents 



of oils 378 



The dogma of the Constancy of Species .... 381 



Differences in chemical constituents may indicate different 



species . . 385 



Toxic principles affected by cultivation , . 386 



