176 Principles of Plant Culture. 
342. Propagation by Seeds is commonly practiced 
with annual and biennial plants; also with perennials in 
which the reproduction of the exact parental form is unim- 
portant, as in the cereals, forest trees, and seedlings intended 
for grafting. This method is also used when it is desired 
to secure variation in the progeny, as in developing new 
varieties (4385). 
343. Propagation by Division of the plant is used 
when it is desired to reproduce the exact parental form, as 
in fruit- and the finer ornamental trees, many flowering 
plants etc.; also, in certain piants that are more readily 
multiplied by division than by seeds, as mint, and many 
other perennial herbs; and in other plants that rarely or 
- never produce seed, as the horse-radish, sugar cane, banana 
etc. 
A — PROPAGATION BY SEEDS 
344. This is the most common method of propagating 
plants. It seemed appropriate to give most of the needed 
directions for planting seeds in the first two sections of 
Chapter Il. We add, therefore, only a few general rules 
deduced from the principles there stated. 
a. The soil in which seeds are to be planted should be thor- 
oughly crumbled, because the seeds must have access to the 
oxygen of the air, or they cannot germinate (31). 
b. The well-crumbled soil should be compactly pressed about 
the seeds, because the seeds cannot absorb moisture rapidly 
unless the seed-case is in contact with the moist soil par- 
ticles at many points (276). 
c. The soil should be moist, but not wet enough to puddle 
(31). If it is wet enough to puddle, the oxygen is likely to ~ 
be shut out from access to the seeds (35). 
