14 



III VEGETABLE LIFE. 



HAVING endeavoured to convey ideas of the ele- 

 ments and organisation of vegetables, we come now to 

 describe that phenomenon called the life, or what may 

 be rationally deemed the causes of the motion and 

 enlargement of these curious organised bodies. 



When we reflect that vegetable matter is com- 

 posed of a mass or compages of areolae, whose mem- 

 branous pellicles are extremely thin, and capable of 

 being distended from an inconceivably small to a 

 larger volume ; and if we consider that those small 

 cells are more or less filled with either a gaseous or 

 aqueous constituent; and farther admit that such 

 constituents are excitable into increased bulk by 

 extraneous agents, we may readily conceive that 

 enlargement of the whole mass must necessarily fol- 

 low such excitement. 



The primitive vesicles or cells are not visible to 

 the keenest eye, nor, indeed, to the most powerful 

 microscope ; and when enlarged to their utmost 

 dimensions they are, in the generality of plants, very 

 diminutive. Even the tubes formed within the cel- 

 lular body are only detectible by optical assistance. 

 This assistance is sufficient to convince us, however, 

 that the cells swell from a smaller to a larger size ; 



