The Continental Monthly, Vol. 3, No. 1 January 1863, page 149 by Various Authors
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dependently of the others? Is not the entire series of parts, organs, and functions bound up in complete and inseparable unity? The vicarious action of one organ for another has been a question among physiologists; and if admitted, as in the case of the salivary glands acting for the kidneys in profuse spitting, and the skin for the liver, the vicarious function can only obtain to a slight degree and in a temporary manner. The destruction of any considerable organ involves the destruction of all the rest. I repeat that the integrity of the physiological unity at the top of the scale, is far more complete, with all its complexity, than is the integrity of the physiological unity at the bottom of the scale, with its marked simplicity of structure. By no sort of legerdemain or surgical skill can we make an individual mammal become two. If we divide it, the whole dies. Not so, however, with some of the lower grades of animal existence. Cut a hydra into thirty or forty pieces, and each piece will become a distinct animal--a facsimile of the original one. In quite an analogous way do a large number of animals at the lower end of the scale propagate, by segmentation and division; one individual becoming two, two four, and so on.
Many examples might be adduced to show the absence of organized unity in the lower orders of the animal creation. Thus, in the annelid, which is composed of a great many similar rings, and is regarded as quite a complex creature, there is so little dependence of one part on another, that a number of the rings may be destroyed without any injury to the rest. The Synapta, when in want of food, will amputate its own body to procure the necessary supply; and it has been observed to repeat the operation, until it 'had by degrees eaten away the whole of its body to keep life in the head.' (Quatrefages.) Such a phenomenon as this is very unlike that presented by the higher animals, which, together with their multiplied individuality of part and function, and their infinite variety of physiognom