158 STATE HORTICULTURAL SOCIETY. 



All parts of plants are composed of small cells. Under a compound micro- 

 scope, a cross-section of a root would show the cells as small circles or poly- 

 gons. Some of the outer cells make an opidennis. Very early in its develop- 

 ment, some of the inner cells become long with tapering extremities. The 

 walls of the long cells become thick and help give strengtli and solidity to the 

 wood. Roots which live for more than one year enlarge by annual layers, in 

 the manner to be described under the structure of stems. At the extremity of 

 a root is the root-cap, back of which only a very little way is the primary 

 meristem, or the place where cells are multiplied to increase the length of the 

 root. Perhaps the twentieth of an inch back from the tip is this growing spot. 

 Roots elongate, then, only by a growth very near the tip or extremity. Cut 

 off this root-tip and it can never grow longer. Almost any portion of a plant 

 may produce roots. The very end of a root is somewhat firm and is composed 

 of cells older than than those back from the extremity. 



I come now to one of the most interesting and wonderful things in connec- 

 tion with vouug roots. 



THE MOTION" OF ROOTS. 



It has long been known that many parts of plants possessed the power of 

 spontaneous motion to a greater or less extent. The late Charles Darwin 

 made some very interesting experiments on this subject. During the past two 

 years I have also made a great many experiments on this subject. 



Roots, stems, and leaves bend to all points of the compass successively with 

 a sort of rolling motion, which Darwin culls circumnutation — a bowing around. 

 Roots grown in damp air in the dark will often make a complete coil, and 

 fiometimes two or three of them. If a piece of gummed paper be placed on 

 one side of the root tip it becomes unusually excited and begins to coil away 

 from the paper, sometimes tying itself into a knot, and often succeeds in rub- 

 bing off the paper. 



The root generally turns downwards, no matter in what direction it first 

 protrudes from the seed. This is not always true, however, in all of the details. 

 In sprouting 400 or more kernels of Indian corn, in damp air, I found the 

 direction taken by the root to vary. 



During the past summer I tested some 700 kernels of Indian corn in loose 

 soil; some in the cellar, some in the garden. In damp air roots frequently 

 came to the surface of the soil, where they apparently grew just as well as 

 they grew below the surface. In the garden, exposed to the sun, it is not 

 unusual for roots of corn and beans to come to the surface and perish. 



I planted some Lima beans with the eye edge uppermost. Many of them 

 came up after a fashion, but they were a good deal confused. They bent 

 around in various directions, and were very interesting to study. 



In the garden nine out of twenty-five, over one-third, of the Lima beans 

 planted with the eye uppermost, sent the radical with all the roots out of the 

 ground, when the whole bean perished. 



Darwin made a large number of experiments on a great variety of seedling 

 plants, including some trees, and all, without exception, showed motion of the 

 roots, stems, and leaves. He placed a young root under a compound micro- 

 scope, where he could see it move. He sprouted some beans and placed the 

 tips of the roots against a smoked glass to see what kind of tracks they would 

 make. The tips, in their downward course, had alternately pressed with 

 greater or less force on the plates, and had sometimes nearly left them. 



