OF ORGANIZED BEINGS. 403 



traction or gravitation, but no one can tell what attraction 

 is. We see one body attracted by or drawn towards an- 

 other, and this is the effect of a certain cause to which 

 we give the name of attraction. We cannot define it 

 except by its results. So it is with life. We know not 

 what life is, but we know what are the effects of that 

 something which we call life. 



There is a regular and gradual progress towards per- 

 fection in the organic world, beginning with the simple 

 plant and passing up to men, and it forms a chain so 

 perfect in all its parts, that it is almost impossible to de- 

 scribe one link without taking into connexion those with 

 which it is united. It would seem easy at first sight to 

 tell the difference between a plant and an animal, and 

 yet to point out the exact difference between the most 

 perfect plant arid the most imperfect or least complicated 

 animal, has been a task for the performance of which the 

 greatest philosophers have almost acknowledged their 

 entire incompetence. If we should ask how you knew 

 a plant from an animal, what answer would you give? 

 Perhaps you would say that animals have eyes and ears, 

 and plants have not. It is true that most anirnals have 

 these organs, but not all. Some animals are destitute of 

 eyes, ears, brain, and even of a heart. You might say 

 that animals require food, but plants require food as well 

 as animals. Plants are organized, and possess the prin- 

 ciple of life to a certain degree as well as animals; but 

 the latter have some properties in addition to those that 

 belong to plants. Animals have the power of locomotion, 

 that is, the power of moving from place to place, but 

 plants are destitute of this power. Plants have simple 

 life as well as animals; but the latter have something 

 added to life, winch we call instinct. All animals have 

 desires ; they determine, they act. They eat at inter- 

 vals, and their food requires time to digest; but plants 

 receive nourishment instantly. Animals are to a certain 

 extent capable of evading danger ; they do this under 

 the impulse of fear ; but plants are subject to everything 

 that moves. We may trace the whole organic chain from 

 the simple plant up to man, and we shall find that there 

 are certain physical properties belonging to all. We 



