124 LETTEHS ON TREES. 



has one ; nor, conversely, is the mammal more or other 

 than a perfect animal because of its possessing such a 

 skeleton. 



5. Jfow, the annual woody layer clearly subserves, 

 physiologically, the purpose of a prop to the young 

 plants developed from the buds — and, economically, 

 that of providing timber for the supply of man's needs. 

 Again, whatever may be its real nature, or however 

 it may grow, it does in point of fact serve also the 

 office of roots to those plants, being the channel 

 whereby the nutritive matters in the soil are conveyed 

 upwards to the growing stems, and leaves, and flowers. 

 And since it thus serves these several purposes, the 

 questions before us are, I think, fairly met and satis- 

 factorily disposed of. The only question will be, whe- 

 ther the woody layer is primarily of the nature of 

 roots, and only secondarily intended as well for a sup- 

 port to the young plants as for the production of tim- 

 ber for man ; or whether it is truly a special forma- 

 tion for the accomplishment of these latter objects, 

 and only virtually, and by adaptation of the nature of 

 roots. 



6. Reduced to this their proper issue, the questions 

 before us have in reality no importance, either specu- 

 lative or practical, in relation to our theory. The 

 woody layer may constitute true roots, or it may be 

 a special formation altogether. Be it which it may, 

 the theory will be noways affected by it. Further, 



