326 
REMARKS ON THE GROWTH OF PLANTS. 
Platanus occidentalis stood in a pleasure-ground, being much valued 
as an ornament, and particularly because it served to hide during 
summer a murky mass of spruce firs. The bole of this tree was 
divided, about four feet from the ground, into two nearly equal parts, 
and formed together a finely-balanced head. In a violent gale of wind 
the outer half of the tree was split off, leaving a scar four feet in length, 
and nearly as wide as the diameter of the remaining trunk, viz. eigh¬ 
teen inches. Forsyth’s plaster was then in high repute; the wound 
was first prepared by smoothing off the rough edges of the bark and 
splinters of the wood with chisels and planes, and a good plaster made, 
secundum artem , and applied, and renewed from time to time for many 
years. Whether this once famous plaster did any other good than 
keep the bare timber dry, we will not assert; but we are quite certain 
that first smoothing and then covering the wound with a good coat of 
tar, with a little tallow and saltpetre added, and renewed if exhaled 
away, would have been a far better application, as well for preventing 
the decay of the naked timber, as for offending insects, which the 
plaster did not do, and healing the wound. 
During the summer of the next year after the accident, the new 
growth of bark and wood began to protrude from beneath the edges of 
the old bark all round the wound, and every summer continued so to 
do; the new growth always proceeding from underneath the lip of the 
former year’s growth, the bark of each year’s growth being annually 
raised up and left behind. The new advancing lip was first whitish 
and very succulent, then green, and afterward brown and woody. It 
advanced, as has already been noticed, with different degrees of cele¬ 
rity ; that at the bottom of the scar slowest, from the upper edge 
fastest, and from each side moderately. It was quite evident, how¬ 
ever, that the drying effects of the sun and air upon the succulent 
lip of the collapsing member was in proportion to its exposure. The 
wound was on the south side of the trunk; and the sun’s rays striking 
so directly upon the lower lip, indurated, and consequently checked its 
expansion much more than the others, especially the upper one, which 
was not shone upon at all. 
So much were we convinced of the hardening effects of the sun’s 
heat and impact of air upon the protruding cambium, that it was 
doubtful whether bark was an identical member, or only a condensed 
surface, (like the crust of bread,) formed by the indurating action of 
the air. But this idea could not be maintained, knowing as we did 
that a new bark, called liber, is every year formed entirely out of 
the reach of the air; but finding that the new member progressed 
faster in darkness than in light, we concluded that the thicker 
