THE MOTION OF PLANTS. 45 



compared with a burrowing auimal, such as a mole, 

 which wishes to penetrate perpendicularly down into the 

 ground. By continually moving from side to side, he will 

 find the easist place for descending. If the earth is damper on 

 one than on the other side, he will turn thither as to better 

 hunting ground. The root, doubtless, can only distinguish 

 water which touches it, having no power to ' scent ' moisture 

 in the distance. It hunts like a blind worm, by feeling, rather 

 than as a hound by scent or vision. The tip alone of the root is 

 sensitive, and when excited causes the adjoining parts to bend. 

 It acts like the brain of one of the lower animals; the brain 

 being seated within the anterior end of the body. And yet the 

 tip of the root of Indian corn, unless held in place, has not 

 power enough to penetrate or indent the thinnest tinfoil. It does 

 not act like a nail when hammered into a board, but more like a 

 wedge of M'ood, which, whilst slowly driven into a crevice, con- 

 tinually expands at the same time by the absorption of water." 



A young stem of corn, the plumule of the seed, bends here 

 and there in every direction, finding the easiest place out of the 

 soil, and after reaching the surface and growing several inches 

 above, it swings about, making the opening at the surface of the 

 ground slightly funnel-shaped. Some plants are sensitive to 

 jarring or friction. Previous mention of this has been made in 

 the chapter on leaves. 



Nature not only sows and distributes the seeds of grasses, but 

 often buries them in the soil. Seeds are generally produced in 

 profuse abundance, enough for perpetuating the species and 

 enough to spare for the food of small animals, and enough to 

 provide against numerous accidents and failures. After the 

 seeds are scattered they are often shaded by other plants which 

 aid in keeping them moist till they germinate. Freezing and 

 thawing, rains and melting snows cover a portion of the seeds ; 

 the wind drifts soil or leaves or other small particles over others. 



