XIV INTEODUCTOET EEMAEKS. 



the greater part of their nourishment from the atmosphere and 

 the moisture suspended in it. By degrees they act on the rocks 

 to which they are attached, and cause their disintegration. By 

 their decay a portion of vegetable mould is formed, and in pro- 

 gress of time a sufficient quantity of soil is produced to serve for 

 the germination of the seeds of higher plants. In this way the 

 coral island is, in the course of years, covered with a forest of 

 coco-nut trees. Thus it is that the most despised weeds lay the 

 foundation for the denizens of the wood ; and thus, in the pro- 

 gress of time, the sterile rock presents all the varieties of meadow, 

 thicket, and forest. 



The Creator has distributed His floral gifts over every part of 

 the globe, from the poles to the equator. Every climate has its 

 peculiar vegetation, and the surface of the earth may be divided 

 into regions characterised by certain predominating tribes of 

 plants. The same thing takes place on the lofty mountains of 

 warm climates, which may be said to present an epitome of the 

 latitudinal distribution of plants. Again, if we descend into the 

 bowels of the earth, we find there traces of vegetation — a vegeta- 

 tion, however, which flourished at distant epochs of the earth's 

 history, and the traces of which are seen in the coal, and in the 

 fossil plants which are met with in difi'erent strata. By the 

 labours of Brongniart, Goeppert, Schimper, and others, these fossil 

 remains have been rendered available for the purposes of science. 

 Many points have been determined relative to their structure, as 

 well as in regard to the climate and soil in which they grew, and 

 much aid has been afi'orded to the Geologist in his investigations. 



The bearings which Botany has on Zoology are seen when we 

 consider the lowest tribe of plants, such as Diatomacese. These 

 bear a striking resemblance to the lowest animals, and have been 

 figured as such by Ehrenberg and others. The observations of 

 Thwaites on Conjugation have confirmed the view of the vegetable 

 nature of many of these bodies. There appear, however, to be 

 many productions which occupy a sort of intermediate territory 

 between the animal and vegetable kingdom, and for the time 

 being the Botanist and Zoologist must consent to joint occupancy. 



The application of botanical science to Agriculture and Horti- 



