8 



THE GARDENER. 



very dissimilar from those of animals, and exist by 

 very different laws. He observes the progress of ve- 

 getation from the time that the embryo of a grain of 

 seed first bursts into life, pushes its roots downwards 

 in search of the nourishment w^hich earth affords, and 

 its stem upwards for the air and light which are equally 

 essential to its existence and development. He sees 

 too that moderate moisture and heat are necessary 

 agents in producing germination, though the philoso- 

 phic causes which render their agency indispensable 

 be unknown to him. He examines the roots, which, 

 from the first stage of life, convey sustenance from the 

 earth to the plant ; and he perceives that the tender 

 fibres stretch out more or less in search of the gaseous 

 and fluid substances which their spongy extremities 

 absorb and convey to the body of which they are 

 such important functionaries. Experience tells him, 

 in proportion as he becomes familiar with the respec- 

 tive natures of plants, in what degree and manner he 

 must supply the earth and manure from which those 

 roots extract the needful sustenance. He perceives 

 that some plants have larger and more numerous 

 leaves than others, and he learns that such derive 

 considerable support from the atmosphere, which they 

 inhale through their various and almost invisible pores. 

 He knows also practically, that some of those require 

 much moisture, while others can thrive in a compara- 

 tively dry atmosphere ; but he rarely understands the 

 organic distinction, which is, that the pores or sto- 

 mates are more numerous and larger in plants de- 

 signed for moist situations, for the purpose of ena- 

 bling them to imbibe liquid more abundantly, and that 

 Ihese pores are far less numerous and active under 

 contrary circumstances : for instance, the field turnip, 

 particularly of the globe kind, requires a humid atmo- 

 sphere ; its very porous leaves cover the surface of a 

 field in England, and produce their corresponding ef- 



