3Q NATURAL HISTORY OF PLANTS. 



benign influence of the sun's rays, at the proper period they germi- 

 nate. It is easy to imagine, that, in this way, many seeds may be 

 brought to places which are not fit for their reception, and thus 

 perish : on this account the wise Author of Nature has provided 

 the annual plants wilh a much greater number of seeds than would 

 otherwise have been necessary. A single plant of Turkey corn 

 (Zea Mays), bears 3000 seeds ; the sun-flower (Helianthus annuus), 

 4000; the poppy (Papaver somniferum), 32,000, and tobacco 

 (Nicotiana iabacum\ 40,320 ; but of so great a number some must 

 necessarily fall on convenient places and be propagated. 



Naked rocky places, on which nothing can grow, are, by the 

 winds, covered with the seeds of -lichens, that by means of the 

 accustomed showers in harvest and spring are induced to germinate. 

 Here they grow, and the rock is spotted with their coloured frond. 

 In time the winds and weather deposit small dust in the rough in- 

 terstices of the rock, and even the decaying lichens leave a thin 

 scurf. On this meagre soil the seeds of mosses are accidentally 

 driven, where they germinate. They grow and produce a pleasant 

 green tuft, which, in tiuie, is fit for the reception of the smaller 

 plants. By the rotting of the mosses and small plants, there arises 

 a thin layer of earth, that in course of time increases, and then 

 becomes fit for the growth of various shrubs and trees, till at last, 

 after many years, where formerly there was nothing but naked rocks, 

 the eye of the traveller is gratified with the sight of extensive woods 

 of the most beautiful trees. Such is the process of Nature ! Gradual, 

 great, and constantly conducive to general good are her operations. 

 Mosses and lichens improve in a similar manner the dry and barren 

 sands. The plants that grow naturally in such soils have almost all 

 creeping and extensively penetrating roots ; or they are succulent 

 and draw moisture from the atmosphere. By means of these plants 

 the sandy soil is made fit for the reception of mosses and lichens, 

 and afterwards changed into good and fertile earth. 



Mosses cover the stems and roots of trees : they have this par. 

 ticular property, that in warm weather they wither, and in wet 

 weather revive again. They readily attract moisture and maintain 

 themselves in the rugged interstices of the bark. From the tree 

 they draw no nourishment ; this they receive entirely from the at- 

 mosphere. In winter they protect the tree from cold, in wet weather 



