POPULAR BOTANY. 453 
voluntary motion, plants are chained to the ground ; but vegetables, in 
return, have been endowed with other advantages, which will counter- 
balance them to a ceitain degree. So, for instance, most of the plants 
are hermaphrodite, combining the conditions of propagation in one 
individual. When most of the land animals produce, as a general rule, 
from one to two young ones per annum, and rarely more than twenty, 
a single plant usually produces during the same time many thousands ; 
nay, ferns, lichens and mosses even several millions of seeds — each con- 
taining the germ of a new vegetable life. 
Besides by seeds, the propagation of plants takes place in a natural 
way, by root-shoots, suckers, runners, layers ; by bulbs, by bending 
over of branches, by dropping of twigs and leaves — without regard to 
the many different artificial manipulations, whose success is really 
astonishing. 
In regard to vitality and reproduction I refer to the fact that animals 
usually die when deprived of integral parts ol their body ; plants retain 
their vitality when totally deprived of their leaves, branches, and even 
stems ; as the grass on meadows, where cattle graze, is eaten off and re- 
produced sometimes once in twenty-four hours. As further evidence for 
my statement, I will mention that plants produce, with the assistance 
of light, air and water, nourishment enough of themselves for the sus- 
tenance of their life and growth, independent of any other succour. 
As soon, for instance, as the frost has interrupted the circulation of 
sap in vegetables, the leaves of most of the trees and shrubs, or the whole 
growth of annual and perennial plants drop to the ground ; and not 
only serve as a natural protection for the roots or seeds against the cold, 
but more warmth is also produced by the chemical process of decomposi- 
tion, for the same end. From the dropped and decaying leaves, brush- 
wood, and other matter, a quantity of humus or leaf-mould is produced, 
of which the rain-water will dissolve the soluble parts and penetrate, 
with them, the bottom ; from which latter the roots will absorb them 
again, in order to use them for the further growth of the plants. 
Besides the nourishment from the humus, the roots also absorb some 
different liquid earth-salts out of the soil; while the leaves absord and de- 
compose on their surface a part of the carbonic acid gas of the atmosphere. 
By this reason the foliage produced in this way weighs always more 
than both the absorbed humus and salt together would amount to. This 
fact has given rise to the introduction of a peculiar mode of manuring. 
In countries, for instance, where manure is scarce, poor fields are sown 
with the seeds of easy and vigourously growing plants, such as peas, 
vetches, lupins, &c, and as soon as they reach their maturity, they 
are plowed under. Now, by the decomposition of these vegetables, the 
ground will gain more manure or humus than the previous crop had 
absorbed from the poor soil, and in this way the fields are very much 
improved. 
3 B 2 
