144 PROPAGATION OF PLANTS. 
times the branch is surrounded with earth in its natural 
position, and detached when it has taken root. _ Propagation 
by runners, as in the Strawberry, may be congidered some- 
what analogous. a 
569. Propagation by slips much resembles the precec 
ing mode. The only difference is, that the branch or 
- is detached from the parent before being made to put out 
roots. The slips or cuttings of most trees that have a light 
white wood, as the Willow, the Ash, or the Poplar, easily 
take root when placed in the earth ; and indeed the Willow 
is reproduced only in this way. It is difficult to propagati 
by slips woods which are very dense and contain much re 
sin, as the Fir and Oak. 
570. These processes for the propagation of plants, are, 
in many cases, preferred to multiplying by seed. Propaga- 
tion by slips or layers always produces the same variety as 
that from which the slip is taken ; so that, if we have a plant 
which produces good fruit, by propagation in either of these 
modes, several may be raised bearing fruit equally good. 
“The tree is always more speedy in bearing fruit when form- 
ed in this way, than when grown from a seed. 
571. It is a remarkable fact, and one which is turned to 
good account in the cultivation of fruit trees, that when the 
tree is raised in this way, the number of seeds in the fruit is 
almost always less than when produced from a seed, so that 
more of the juices and strength of the plant are expended in 
perfecting this fruit. The Vine, when raised by seed, has 
four seeds in each grape; but frequently only two, when 
“propagated by layers. The Sugar-cane, which is propagated 
ina nearly similar manner, bears no seed at all, but the 
other parts of the plant are richly developed. 
© 872. ‘Thus, by a singular control over their mode of 
growth, which is also exhibited in the case of viviparous 
plants, vegetables are enabled to adapt the number of seeds 
to the demand for them—the demand depending on the 
number of other sources for propagation which they ma 
Bee 
. 
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