4 1 6 Analogy between Plants and Animals. 



One very remarkable point of difference between animals 

 and plants is that which has been before alluded to, the much 

 greater provision which nature has made for the propagation of 

 the latter than of the former. Plants not only produce immense 

 quantities of seeds, which are distributed by the winds and 

 waters, by animals, and by various causes ; but they extend 

 themselves by shoots, which run on or under the surface of 

 the ground, as in the case of the strawberry, the raspberry, &c. ; 

 and they produce buds, each of which, by human art, can be 

 rendered equivalent to a seed, either by planting it (with a small 

 portion of the plant from which it is taken) at once in the ground, 

 or by inserting it in another plant of the same family. Hence, 

 the great facility with which plants are multiplied both by na- 

 ture and art ; with the exception of a few, in which the process of 

 propagation by artificial means is comparatively difficult. 



Another remarkable difference, also before alluded to, between 

 plants and animals is, the absolute necessity of light to plants 

 during the whole period of their existence. There are many 

 animals of the lower description, such as worms, to which light, 

 so far from being necessary, is injurious ; and there are instances 

 of even the more perfect animals having lived for several years 

 without the presence of light, either natural or artificial. Light 

 is not necessary for either the functions of the stomach, brain, 

 or lungs, in animals : but in plants, though it is equally unne- 

 cessary for the functions of the root and the collar, it is essen- 

 tially so for those of the leaves ; and the leaves are necessary 

 to the elaboration of the sap, and, consequently, to the nourish- 

 ment of the plant. A plant, therefore, from which the leaves 

 are continually stripped as soon as they are produced, soon 

 ceases to live. Small and weak plants, from which the leaves 

 are taken off as they are produced, will die in a single sea- 

 son ; and this practice, continued for two seasons, will kill, or 

 nearly so, the largest tree. If, instead of stripping a plant of 

 its leaves, the leaves are produced in the absence of light, and 

 light never admitted to them, the effect will be precisely the same. 

 Seeds germinated, or plants struck from cuttings, in the dark, 

 will not exist a single season ; nor will trees, or tubers, such as the 

 potato, placed in an apartment from which all light is excluded, 

 live more than two seasons. Hence, the importance of light to 

 plants can scarcely be overrated ; for, while it has been proved 

 that plants, even of the most perfect kind, will live for many 

 months, or even years, in glass cases in which very little change 

 of air has taken place, there is no instance of plants, even of 

 the lowest kind, such as ferns and mosses, living for any length 

 of time without light. Without light, there can be no green in 

 leaves, no colour in flowers, and neither colour nor flavour in 

 fruits. 



