296 VITALITY OF SEEDS. 
clayey soil remaining from the streams of mud, the conditions 
of growth which the other soil of the mountain refused them.” 
This is probable enough, but it is hardly less so that the flowing 
mud brought them up to the influence of air and sun, from depths 
where a previous convulsion had buried them ages before. 
Seeds of small sylvan plants, too deeply buried by successive 
layers of forest foliage and the mould resulting from its decom- 
position to be reached by the plough when the trees are gone 
and the ground brought under cultivation, may, if a wiser pos- 
terity replants the wood which sheltered their parent stems, 
germinate and grow, after lying for generations in a state of 
suspended animation. 
Darwin says: “On the estate of a relation there was a large 
and extremely barren heath, which had never been touched by 
the hand of man, but several hundred acres of exactly the same 
nature had been enclosed twenty-five years previously and 
planted with Scotch fir. The change in the native vegetation 
of the planted part of the heath was most remarkable—more 
than is generally seen in passing from one quite different soil 
to another; not only the proportional numbers of the heath- 
plants were wholly changed, but twelve species of plants (not 
counting grasses and sedges) flourished in the plantation which 
could not be found on the heath.” * Had the author informed 
us that these twelve plants belonged to species whose seeds 
enter into the nutriment of the birds which appeared with the 
young wood, we could easily account for their presence in the 
soil; but he says distinctly that the birds were of insectivorous 
species, and it therefore seems more probable that the seeds had 
been deposited when an ancient forest protected the growth of 
the plants which bore them, and that they sprang up to new life 
when a return of favorable conditions awaked them from a sleep 
of centuries. Darwin indeed says that the heath ‘ had never 
been touched by the hand of man.” Perhaps not, after it be- 
came a heath ; but what evidence is there to control the general 
presumption that this heath was preceded by a forest, in whose 
* Origin of Species, American edition, p. 69. 
