59e PRINCIPLES OF BOTANY, ETC. 
inilar changes in our atmosphere favour their growth, 
In our lies besides the algae and mosses, three 
great annual storms assist plants in their growth, viz. 
in spring, in the middle of summer, and in autumn. 
Besides their great use in clearing the atmosphere, 
they have a peculiar one in the vegetable world. In 
spring storms drive the seed, which has during 
winter perhaps remained dry and hanging on the 
stern to a distance. In summer they carry off the 
seeds of vernal plants which have just ripened; and 
in autumn those which in summer or at the end of 
summer attained their maturity. Moles and grubs 
and dew-worms soften the ground and prepare it 
for the reception of thte seed; a hard shower pushes 
it deeper info the ground, where through the be- 
neficial rays of the sun it can germinate at the pro- 
per time. How easily seeds may thus come to places, 
totally unfit for their reception, and how many on 
that account are lost, is easily conceived. Hence it 
appears, that the wise Author of things gave te an- 
nual plants a proportionally greater number of seeds 
than at the first view would appear necessary. One 
plant, for instance, of mays, (Zea Mays), has 3000” 
seeds; a sun flower, (Helianthus annuus), 4000 > 
Poppy, (Papaver sommiferum ), 32,000 ; and tobacco, 
(Nicotiana tabacum), 40,820. Of so gréat a num- 
ber of seeds, some must necessarily get to the soil 
they require to propagate their’ species. 
Naked barren rocks become, by means of the 
wind, covered with the seeds of algae, which in 
spring and autuinn when they ripen are, by showers, 
common at that season, brought to germinate. They 
crow 
