The ComjDarative Chemistry of our Forest Trees. 



By P. Q. Keegan, LL.D. 



By the chemistry of trees is meant not the special detection and 

 demonstration of the chemical forces which exert energy within the 

 living arboreal organism, but rather the detection and assignment of 

 such separable and distinctive organic and inorganic bodies as are 

 incidental to the vital processes thereof, whether these bodies furnish 

 the stroma of the actual life, or are merely bye- or waste- products 

 of the spent and exhausted activities. The tree, indeed, may be 

 regarded as the outward and visible sign of an inward and wholly 

 invisible force. The capital force is the mysterious one called "vital;" 

 but chemical forces and their visible or detectable products, which here 

 alone concern us, are set agoing thereby, and are manifested as a heritage 

 or inevitable consequence. Nevertheless, it is absolutely certain that 

 some of the most brilliant, beautiful, and distinctive constituents of the 

 tree — of its stem, leaf, and flower — are not the results of any chemical 

 processes known to us, and cannot possibly be artificially reproduced by 

 the most capable and dexterous application of the latest and most 

 approved synthetic methods and expedients. 



The arborescent forms of the forest flora of the British Islands are 

 not very numerous, but (native and denizen species included) they are 

 sufficiently varied to render an account of their chemical constituents 

 exceedingly interesting and instructive. If, for instance, we desire to 

 study the chemical characteristics of the Gymnosperms, we can forth- 

 with fasten on that stately and sombre-foliaged tenant of our upland 

 wastes and craggy mounds known as the Scotch Fir (Pinus sylvestris). 

 Perhaps we have been accustomed to consider the leaf as the most 

 vigorously active of the vegetable organs, but here we see that a mighty 

 portion of the energy is delegated to the woody tissues. For what is 

 the meaning of the resinous matter which is so characteristic a con- 

 stituent of the Coniferae, and the origin of which has been the theme 

 of such acute and prolonged controversy ? Some specially active 

 mother-cells containing an opaque plasma, and situated in the external 

 heart-wood, divide and divide again with great energy, separating from 

 the adjoining tissue, and forming four to eight or more daughter cells 



53 



