36 ON THE PLACE OF MAN IN THE SCALE OF BEING. 



tons are often found with no obvious traces of the animals to which they be- 

 longed, they have been accounted Vegetable growths. This idea receives 

 confirmation from examination of their intimate structure ; for they are com- 

 posed of a tissue which bears more resemblance to the cellular tissue of Plants 

 than to the areolar tissue of the higher Animals. There is not the least doubt, 

 however, as to the Animal origin of the greatest part of these plant-like struc- 

 tures ; and one group only, that of Corallines, remains a source of much 

 perplexity to the Naturalist. 



19. The affinity, however, between the lowest Radiata and Plants, in regard 

 to the vital phenomena they exhibit, is still more close than that manifested 

 by their structure. Although, in the higher groups, movements may be con- 

 stantly witnessed, which evidently indicate consciousness and voluntary power, 

 this js far from being the case in the lower. There are many tribes, whose 

 reception of food, growth, and reproduction, are not known to be accompanied 

 by any phenomena which distinctly indicate their animal character. The 

 most violent lacerations produce no signs of sensibility ; and the movements 

 they occasionally exhibit have not so much of a spontaneous character as those 

 which are performed by many plants. This is the case, for example, with the 

 Sponge tribe, and also with a number of microscopic species." So doubtful is 

 the nature of these beings, that their Animal or Vegetable character is rather 

 to be decided by their affinity with species known to belong to one or the 

 other kingdom, than in any other way. 



20. It is very different, however, in regard to the higher Radiata. Even 

 among the Zoophytes (as the plant-like animals just alluded to are commonly 

 termed) there are some species which are unattached during the whole period 

 of their lives, and have a power of voluntarily moving from place to place, 

 such as is never possessed by plants. And in the highest class, the Echino- 

 dermata, including the Star-fish, Sea Urchin, &c., we meet with a considerable 

 degree of complexity of structure, and a corresponding variety of actions. Still, 

 except in those species which connect this group with others, the same cha- 

 racter of radial or circular symmetry is maintained throughout ; and in no ani- 

 mal is it more remarkable than in the common Star-fish. It is exhibited alike 

 in its internal conformation and external aspect. The mouth, placed in the 

 centre of the disk, leads to a stomach which occupies the greatest part of the 

 cavity of the body ; and this sends prolongations into the (arms which are 

 exactly alike in form), and occupy a precisely similar position in every one. 

 Each arm is furnished, on its under side, with a curious apparatus for locomo- 

 tion, consisting of a series of short elastic tubes, which are prolonged through 

 apertures in the hard envelop, from a series of vesicles placed along the floor 

 (as it may be termed) of the ray. The system of vessels for absorbing nutri- 

 ment and conveying it through the system, is also disposed upon the same 

 plan ; and the same may be said of the nervous system, and of the only organs 

 of special sensation which this animal appears to possess, the rudimentary 

 eyes, of which one is found at the extremity of each ray. 



21. Amongst other results of the repetition of similar organs, so remarkable 

 in this group, is this, that one or more of them may be removed without per- 

 manent injury to the whole structure, and may even develop themselves into 

 an entire fabric. Thus in the Star-fish, instances are known of the loss of one, 

 two, three, and even four rays, which have been gradually reproduced ; the 

 whole process appearing to be attended with little inconvenience to the animal. 

 In some species of isolated Polypifera, such as the common Sea- Anemone, and 

 Hydra (Fresh-water Polype), this power of reproduction is much greater. 

 The Hydra may be cut into a large number of pieces (it is said as many as 

 40), of which every one shall be capable of developing itself in time into a per- 

 fect polype. The Sea- Anemone, when divided either transversely or vertically, 



