Lesson xxxiv.] VEGETATION. 231 



which the Plants lake little from the earth ; but 

 as soon as the ear begins to be formed, thty lose 

 their softness, and diminish in thtir attractive 

 power. The radical fibres are then more vigorously 

 employed in extracting the oily particles from the 

 tarth, for the nourishment of the plant. 



The leaves of Plants serve not only to imbibe 

 the dew and rain, which contain salt, sulphur, &c. 

 but they serve also as excretory ducts to separate 

 and carry off ihe redundant watery fluid, which 

 by being long detained in the Plants, would turn 

 rancid and prejudicial to them. The annual sun- 

 flower is an extraordinary instance of this fact : it 

 is said to perspire nineteen times as much as a 

 man in twenty-four hours. Fine weather encou- 

 rages the perspiration of Vegetables; but in htavy, 

 moist, and wet weather the inhalation is greatest. 

 The effluvia of Plants is thought unwholesome to 

 persons of delicate constitutions; but particularly 

 so at night, and in a dull state of the atmosphere : 

 the matter perspired by the yew tree, in particular, 

 is said to be very noxious. 



Let us now endeavour to illustrate the subject of 

 Vegttation, by taking a view of what happens to a 

 bean after it has been committed to the earth. In 

 a few days, sooner or later, according to the tem- 

 perature of the weather and disposition of the soil, 

 the external coverings open at one end, and dis- 

 close to -.he naked eye part of the body of the grain. 

 This substance consists of two lobes, between 

 which the seminal Plaut is securely lodged. Soon 



after 



