. Principles of human physiology : with their chief applications to pathology, hygiene, and forensic medicine : especially designed for the use of students. er, as those which are performed by many is the case, for example, with the Sponge tribe, and also with a num-ber of microscopic species. So doubtful is the nature of these beings, thattheir animal or vegetable character is rather to be decided by their affinitywith species known to belong to either kingdom, than in any other way. 20. It is very different, however, in regard to the higher Radiata. Evenamong the Zoophytes (as th
. Principles of human physiology : with their chief applications to pathology, hygiene, and forensic medicine : especially designed for the use of students. er, as those which are performed by many is the case, for example, with the Sponge tribe, and also with a num-ber of microscopic species. So doubtful is the nature of these beings, thattheir animal or vegetable character is rather to be decided by their affinitywith species known to belong to either kingdom, than in any other way. 20. It is very different, however, in regard to the higher Radiata. Evenamong the Zoophytes (as the plant-like animals just alluded to are com-monly termed) there are some species which are unattached during thewhole period of their lives, and have a power of voluntarily moving fromplace to place, such as is never possessed by plants. And in the highestclass, the Echinodermata, including the Star-fish, Sea Urchin, &c, wemeet with a considerable degree of complexity of structure, and a corre-sponding variety of actions. Still, except in those species which connectthis group with others, the same character of radial or circular symmetry Fig. Asterias aurantiaca, with the upper side of the hard envelope removed: a, central stomach; b,coeca upon its upper surface, probably answering to the liver; c, c, coscal prolongations of stomachinto rays; (?,•. the same empty; d, the same opened; e, under surface, showing vesicles of feet; f,vesicles contracted, showing skeleton between them. 38 ON THE PLACE OF MAN IN THE SCALE OF BEING. is maintained throughout; and in no animal is it more remarkable than inthe common Star-fish. It is exhibited alike in its internal conformationand external aspect. The mouth, placed in the centre of the disk, leads toa stomach which occupies the greatest part of the cavity of the body; andthis sends prolongations into the arms, which are exactly alike in form,and occupy a precisely similar position, in every one. Each arm is fur-nished, on its under
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