The First Land Plants 
hurriedly form spores and await better times. The whole 
complex life of the soil is almost at a standstill. 
Then the rain stops, and sun and wind dry up the 
surface so that the water evaporates and the air passages 
become free again. Then at once, with the advent of 
revivifying oxygen, the whole complex machinery of 
underground life awakes again to vigorous activity and 
is in full working order. 
Catastrophes are often blessings in disguise, as, ¢.g., a 
hard frost, which not only pulverises the soil but is in 
the end most beneficial. 
The fungi vanish, turning black at the first touch of 
frost ; the leaves and stems of summer herbaceous plants 
fall off or become sodden, flaccid, and horrible, and 
nothing is left but the roots and underground stems, 
with their carefully stored up starches and proteids. 
The bacterial population is massacred wholesale, for 
only a few of the strongest and hardiest microbes refuse 
to be killed. 
But when the spring comes, the new bacterial races 
are all specially selected stocks, and the best of their 
kind. So also are the fungi, and even the weed-seeds 
and flower-roots. It follows that the new population 
starts strong and efficient on another year of adventure 
and hard work, for all its forefathers were healthy and 
sound, 
When, for instance, such a manure as carbon bisul- 
phide is used on arable land, the first result is a horrible 
diminution of the bacterial population, but after a time 
the bacteria begin suddenly to increase in numbers and 
flourish exceedingly. This is explained by the fact that 
all except the very strongest have been slain. 
In a recent report on the grouse disease on over- 
stocked moors, the usual sequence of disastrous years, 
followed by a sudden run of good seasons, seems to be 
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