Analogy between Plants and Animals. 4 1 3 



the external members of an animal, may be injured, mutilated, 

 and even diseased ; but, if the soil and the stomach be invigo- 

 rated, and placed in a healthy state, the whole plant or animal 

 will soon recover from the injuries it has received, so as to per- 

 form all the functions necessary to its existence. The first step, 

 therefore, in cultivating or in improving plants, is, to improve 

 the soil in which they grow. 



In all vertebrate animals, there is a part at the back of the 

 neck, between the spinal marrow and the brain, where a serious 

 injury will occasion immediate death. There is a corresponding 

 point in plants, between the root and the stem, which is called 

 the neck, or collar ; and at this point plants may be more readily 

 injured than any where else. Most plants, also, may be killed, 

 by covering this point too deeply with soil. In all seedling 

 plants, this neck, or vital point, is immediately beneath the seed 

 leaves ; and, if the plant be cut over there when in a young state, 

 the part which is left in the ground will infallibly die. In old 

 plants, however, and particularly in herbaceous plants which 

 have creeping stems, and in various kinds of trees and shrubs, 

 the roots, after a plant has attained a certain age, become fur- 

 nished with buds ; and, when the plant or tree is cut over by the 

 collar, these dormant buds are called into action, and throw up 

 shoots, which are called suckers. No sucker, however, is ever 

 thrown up by the roots of a plant cut through at the collar 

 while in its seed leaves. The branches of a tree may be all cut 

 off close to the trunk, and the roots also partially removed ; but, 

 if the collar remain uninjured, the plant, in suitable soil, and 

 under favourable circumstances, will throw out new roots and 

 shoots, and, in time, will completely recover itself. 



There are some plants of the herbaceous kind (such as the 

 horseradish, for example) that do not suffer, even if their collar 

 should be buried 2 ft. or even 3 ft. ; but by far the greater num- 

 ber of plants (such as the hepatica, the common daisy, the com- 

 mon grasses, &c.) are killed by having the collar covered 2 or 

 3 inches ; and nothing is more injurious to woody plants, whether 

 large or small. It is easy to destroy a large tree by heaping up 

 earth round the base of its trunk ; and easy to prevent a small 

 one from growing, by lifting it, and planting it 6 in. or ift. 

 deeper than it was before. Hence the great importance of not 

 planting any plant deeper in the soil than it was before taking it 

 up. The cause why plants are so much injured by burying the 

 collar has not, as far as we know, been physiologically explained ; 

 but it probably proceeds from the want of the action of air on 

 the collar, or on that part of the stem which is immediately 

 above it ; or from the pressure of the soil upon that vital point. 



The next point of analogy between plants and animals, which 

 it may be useful to notice, is that between the lungs and the 



