INTRODUCTION. V 



and the one in its effort to ascend perpendicularly, and the other to descend, 

 they had formed a perfect spiral. But although the natural tendency of the 

 root is downwards, if the soil be dry, and any damp substance be placed 

 above, the roots will ascend to reach it. Or, if the shrub or tree has taken 

 root upon the side of a precipice, and the soil be somewhat nearer above 

 than below, the plant will send a root in a straight line to meet it. In sup- 

 port of the above fact, we would cite a singular coincidence, or freak of na- 

 ture, fuUy illustrating the natural instinct of the vegetable creation ; and 

 one which, perhaps, may have been witnessed by some of our readers. Ujion 

 the precipice, or side of the perpendicular rocks of the natural bridge in 

 Virginia, are to be seen goodly-sized trees, which first took root in the cre- 

 vice of the rock some several feet down from the surface of the earth ; grow- 

 ing in this situation until the trees had exhausted all the nourishment which 

 coidd be obtained in those crevices, and the distance being extremely great 

 beneath, they, in seeking for the necessary support of life, sent up numerous 

 roots to the rich soil above. The curiosity of many a visitor to this remark- 

 able place has been excited in regard to the situation and sustenance of those 

 trees ; there they now stand as living monuments in proof of the powerful 

 and natural instinct of plants. 



A tree growing from an old wall, or cleft of a rock, will, as soon as i*; 

 has exhausted the surrounding soil, send a stem or root down to the soil be- 

 neath ; and Stevens, in his searches ambng the ruins of Central America, 

 found magnificent trees, of extraordinary size and of a great height, living 

 upon the very tops of some of the highest walls of the deserted edifice of a 

 lost race, which having sent stems down to the soil on each side of the 

 wall, and forming by this means a firm support, and being thus, as it were, 

 strapped together by living cables, they remain to this day in their full vigor 

 and strength. 



The plants in a hot-house do not direct their leaves to the stove in 

 quest of heat, nor to the door in quest of air, but to the sun in quest of light. 

 Plants in a cellar or dark room struggle towards the light ; plants in an 

 area turn the upper surface of their leaves towards it, and, on the contrary, 

 their roots suddenly avoid it. 



The tendril of a vine, or the stem of a creeping plant, never makes any 

 turn until it comes in contact with some object around which it can entwine ; 



