39 



CHAPTER I. 



ON THE PLACE OF MAN IN THE SCALE OF BEING. 



1 . Distinction between Animals and Plants. 



1. IN entering upon the general survey of the Animal Kingdom, which it 

 is desirable to take before we consider in detail any particular member of it, 

 the question naturally arises, how is the Animal distinguished from the 

 Vegetable ? There is no difficulty in replying to this, if we keep in view 

 merely the higher tribes of each division ; no one, for example, would be in 

 any danger of confounding a Whale with a Palm, or an Elephant with an 

 Oak. It is when we descend to the opposite extremity of the scale, that we 

 encounter the greatest difficulty ; from the circumstance that the distinguish- 

 ing characters of each kingdom disappear, one after another, until we are 

 reduced to those which seem common to both. So completely is this the 

 case, that there are many tribes which cannot, in the present state of our 

 knowledge, be referred with certainty to either one division or the other. We 

 are accustomed to think of Animals as beings, which -not only grow and 

 reproduce themselves, but which also possess the power of spontaneously 

 moving from place to place, and which are conscious of impressions made 

 upon them : and we usually regard Plants as beings which are entirely des- 

 titute of sensibility and of the power of spontaneous motion, going through 

 all their processes of growth, reproduction and decay, alike unconscious of 

 pleasure and of pain, and devoid of all power of voluntarily changing their 

 condition. Such a definition is probably the most correct that we can employ ; 

 but great difficulties lie in the way of its application. There are many tribes 

 which possess a general structure more allied to that of beings known to be 

 Animals, than to that of any Plants ; and which yet present no decided indi- 

 cations, either of sensibility or of voluntary power. Such is the Sponge, 

 the fabric of which closely corresponds with that of many Alcyonian Polypes, 

 whose animality is undoubted ; whilst there are no known Vegetables to 

 which it presents any near resemblance : and yet neither observation nor 

 experiment has ever succeeded in proving that the Sponge feels or spontane- 

 ously moves. On the other hand, many Vegetables perform evident move- 

 ments, which, at first sight, appear to be spontaneous, as if they indicated 

 sensibility on the part of the being that executes them. Such movements, 

 however, can in some instances (as in that of the Sensitive-Plant, or of the 

 Venus's Fly-trap), be referred to a sort of mechanism, the action of which 

 does not involve sensibility, and which may be compared with the many 

 movements (such as that of the heart) that are constantly taking place in the 

 bodies of the highest animals, without their consciousness ; and in other cases 

 (as in the Oscillatorise) they are so rhythmical, as to impress the observer 

 with the idea that they are rather the result of some physical, than of any 

 mental, influence. In this respect they correspond with the motions of the 

 constantly-vibrating cilia; which cover the surface of the mucous membranes 

 of Animals ; and which have been recently detected in the reproductive par- 

 ticles of certain among the lower tribes of aquatic Plants. 



