92 PLANT LIFE ON THE FARM. 
Growth and development may go on together at the 
same time, as we see in an oak tree, which puts forth its 
midsummer shoots at the same time that it is ripening 
its acorns and consolidating the new wood; but in an 
herbaceous plant, like the wheat, as development pro- 
ceeds growth ceases—at least, to a great extent. So in 
the case of such plants as the turnip, the mangel, and 
the hop, when the plant commences to enter upon the 
flowering stage, then changes—not merely of bulk, but 
of outward form, and to some extent of inward construc- 
tion and chemical composition—occur. So, as the soft 
tissues harden into solid wood by deposit of woody mat- 
ter in their wood cells, development takes place ; and, as 
the water and the salts taken up by the roots and the 
gases inspired by the leaves act and re-act upon one 
another—aided or not, as the case may be, by the agency 
of light—various changes occur which may be included 
under the head of development. Development, then, is 
morphological in so far as it relates to the conformation 
of the plant, chemical or physical—in so far as it includes 
the chemical and physical changes which accompany the 
passage from the young to the old, from the crude and 
imperfect to the complete and mature. The conditions 
which favor development in the sense here understood 
are thus more® or less opposite to those which foster 
growth. Gardeners recognize this by affording plenty of 
water and sufficient heat to their plants when growing, 
and by reducing the amount of water as the plant is about 
to produce flower, fruit, and seed. They apply liquid 
manure in the growing stage, but withhold it in the 
ripening period. They root-prune their fruit trees when 
growth is too vigorous and fruit production too scanty. 
They check rampant growth by keeping the roots in 
small-sized pots. ‘The farmer unfortunately has not the 
same control over his plants that the gardener has, but 
he is careful as to the time when he applies manure. He 
