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



doubtful is the nature of these beings, that their Animal or Vegetable charac- 

 ter )s rather to be decided by their affinity with species known to belong to 

 one or the other kingdom, and by the chemical composition of their tissues, 

 than in any other way. . 



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

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

 monly termed), there are some species which are unattached during the 

 whole period of their lives, and which have a power of voluntarily moving 

 from place to place, such as is never possessed by plants. And in the high- 

 est class, the Echinodermata, including the Star-fish, Sea Urchin, &c., we 

 meet with a considerable degree of complexity of structure, and a correspond- 

 ing variety of actions. Still, except in those species which connect this group 

 with others, the same character of radial or circular symmetry is maintained 

 throughout ; and in no animal is it more remarkable than in the common Star- 

 fish. It is exhibited alike in its internal conformation and in its 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 whicli oc- 

 cupy a precisely similar position in every one. Each arm is furnished, on its 

 under side, with a curious apparatus for locomotion, consisting of a series of 

 short elastic tubes, which are prolonged through apertures in the hard enve- 

 lope, from a series of vesicles placed along the floor (as it may be termed) of 

 the ray. The system of vessels for absorbing nutriment 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. 



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

 in the Radiated group, is this, that one or more of them may be removed with- 

 out permanent injury to the whole structure, and may even develope them- 

 selves 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 repro- 

 duced ; 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 perfect polype. The Sea-Anemone, when divided either trans- 

 versely or vertically, still lives ; and each half produces the other, so as to re- 

 form the perfect animal. This is another character which shows the affinity 

 of the Radiata to the Vegetable kingdom ; and there is yet another, derived 

 from their mode of reproduction. In many Polypifera, we observe a propa- 

 gation by buds, in all respects conformable to that which plants effect, and 

 quite different from the regular multiplication by distinct germs. This gem- 

 miparous reproduction, as it is called, takes place, not only in the compound 

 Polypifera, whose plant-like structures are extended by it, but also in some 

 isolated species, such as the Hydra ; from the body of which one or more young 

 polypes bud forth at the same time ; and these buds may themselves put forth 

 another generation, previously to their separation from their parent. This 

 kind of reproduction is not seen anywhere else in the whole Animal kingdom, 

 except in a few of the lowest Mollusca and Articulata, which border most 

 closely on the Radiata. 



10. In the lowest animals of this group, such as the simplest forms of Po- 

 lypes, we find the whole body to consist of nothing else than a stomach, fur- 



