448 CHARACTER OF VEGETABLE VITALITY. CHAP. XI. 



as resembling the Violet : much less can it be the 

 Sun-flower of the moderns, which is a native of 

 America, and could not consequently have been 

 known to Ovid ; so that the true Hdiotropium of 

 the ancients is perhaps not yet ascertained. 



Bonnet has further remarked that the ripe ears 

 of Corn, which bend down with weight of grain, 

 scarcely ever incline to the north, but always less or 

 more to the south ; of the accuracy of which re- 

 mark anyone may easily satisfy himself by looking 

 at a field of Wheat ready for the sickle ; he will 

 find the whole mass of ears nodding, as if with one 

 consent, to the south. 



And in The cause of the phenomenon has been supposed 

 co^T d to be a contraction of the fibres of the stem or 

 flower-stalk on the side exposed to the sun ; and 

 this contraction has been thought by M. De La Hire 

 and Dr. Hales to be occasioned by an excess of 

 transpiration on the sunny side ; which is probably 

 the fact, though there seems upon this principle to 

 be some difficulty in accounting for its returning at 

 night ; because if you say that the contracted side 

 expands and relaxes by moisture, what is it that 

 contracts the side that was relaxed in the day ? The 

 moisture, of which it is no doubt still full, would 

 counteract the contraction of its fibres, and pre- 

 vent it from resuming its former position in the 

 morning. 



