282 
PHYSIOLOGY. 
BOOK II. 
to be from it either conveyed to the root, or distributed 
horizontally by the medullary rays to the centre of the stem. 
At the end of the year the same phenomena occur as took 
place the first season : wood is gradually deposited by slower 
degrees, whence the last portion is denser than the first, and 
gives rise to the appearance called the annual zones : the new 
shoot or shoots are prepared for winter, and are again 
elongated cones, and the original stem has acquired an 
increase in diameter proportioned to the quantity of new 
shoots which it produced, new shoots being to it now, what 
young leaves were to it before. 
IV. The third year all that took place the year before is 
repeated : more roots appear sap is again absorbed by the 
unfolding leaves ; and its loss is made good by new fluids 
introduced by the roots and transmitted through the alburnum 
or wood of the year before ; new wood and liber are deposited 
by matter sent downwards by the buds ; cambium is exuded; 
the horizontal developement of cellular tissue is repeated, but 
more extensively ; wood towards the end of the year is formed 
more slowly, and has a more compact character ; and another 
ring appears indicative of this year’s increase. 
In precisely the same manner as in the second and third 
years of its existence will the plant continue to vegetate, till 
the period of its deca}^, each successive year being a repetition 
of the phenomena of that which preceded it. 
V. After a certain number of years the tree arrives at the 
age of puberty : the period at which this occurs is very 
uncertain, depending in some measure upon adventitious 
circumstances, but more upon the idiosyncrasy, or peculiar 
constitution, of the individual. About the time when this 
alteration of habit is induced, by the influence of which the 
sap or blood of the plant is to be partially directed from its 
former courses into channels in which its force is to be applied 
to the production of new individuals rather than to the exten- 
sion of itself; about this time it will be remarked that 
certain of the young branches do not lengthen, as had been 
heretofore the wont of others, but assume a short stunted 
appearance, probably not growing two inches in the time 
which had been previously sufficient to produce twenty inches 
