ON THE PHYSICAL STRUCTURE OF PLANTS. 47 
sessile, or without any; while the inferior oak has sessile acorns, and 
leaves with lengthened foot-stalks.”— Burnett. Figs, a and b . 
Others believe that it is the soil on which the tree grows which 
imparts the durable quality to the wood; and hence it has been said 
that, unless oak grows on land having a substratum of blue clay, or 
loam strongly impregnated with iron, the timber will be inferior. The 
same opinionists add that, since it has been so much the fashion to 
plant oak for the embellishment of country seats and improvement of 
estates, and, consequently, on all kinds of well-prepared soil, whether 
fit for the tree or not, has been the cause of much worthless timber 
being thrown on the market. 
There is yet another idea on which some very able arboriculturists 
have differed, and this is relative to the quickness or slowness of the 
growth. One maintains that the quicker the tree arrives at a market¬ 
able bulk, the better the timber will be both as to strength and 
durability. A directly opposite opinion is held by others, w r ho say 
that the slower the growth the closer the grain; and, of course, they 
think that the timber must be at once both more solid and more 
ponderous. 
Ship-builders and carpenters have been applied to to decide this 
question, but they, knowing nothing of the growth of trees, w T ere 
incompetent judges. Timber-dealers and purveyors of timber for the 
navy seem to lean to the first opinion, namely, that wherever the 
trees grow most freely, there the finest timber is met with ; and 
they mention several districts of heavy land where the finest oak 
is grown. 
That the quickest grown timber is coarser in the grain, is very 
obvious, and that it is also stronger and more durable, is highly pro¬ 
bable, because it is the amplitude and consequent strength of the fibrous 
tissue which constitutes the excellence of timber, and not the cellular 
portions, which, though they are more dense, and work more mildly 
