Licence: Public Domain Mark
Credit: The works of John Hunter / edited by James F. Palmer. Source: Wellcome Collection.
Provider: This material has been provided by the Royal College of Physicians of Edinburgh. The original may be consulted at the Royal College of Physicians of Edinburgh.
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![of the arrangement, for action is not confined to muscle, the nerves also have action arising from the arrangement of their living particles*. The principle of life has been compared to the spring of a watch, or the moving powers of other machinery; but its mode of existence is en- tirely different. In a machine the power is only the cause of the first action or movement, and thereby becomes the remote cause of the second, third, &c.; but this is not the case with an animal; animal mat- ter has a principle of action in every part, independent of the others, and whenever the action of one part (which is always the effect of the living principle,) becomes the cause of an action in another, it is by stimulating the living principle of that other part, the action in the se- cond part being as much the effect of the living principle of that part as the action of the first was of the living principle in it. The living prin- ciple, then, is the immediate cause of action in every part; it is therefore essential to every part, and is as much the property of it as gravity is of every particle of matter composing the whole. Every individual par- ticle of the animal matter, then, is possessed of life, and the least imagin- able part which we can separate is as much alive as the whole,. The first, and most simple idea of life, I have observed, is its being the principle of self-preservation, preventing matter from falling into dissolution,—for dissolution immediately takes place when matter is deprived of it; and the second is its being the principle of action. These are two very different properties, though arising from the same prin- ciple, the first being capable of existing independently of the second; for it may be observed, that it is not necessary for the preservation of animal matter that there should be action in all parts, for many parts of an animal appear to have little action, yet they are as much endued with life as the more active parts; such, for instance, as tendons, elastic ligaments, &c. A fresh egg is a body which, it must be allowed, has no vital action; yet an egg is as much alive as an animal, which I shall endeavour to * [This opinion concerning the unity of the principle of life has already been shortly adverted to. It may perhaps be illustrated by referring to the powers of common mat- ter, which are not one, but many. There seems good reason for considering the dif- ferent kinds of attraction as modifications of a higher principle, and the best reason for believing that magnetism, common electricity, and galvanism proceed from the same source, or at least are essentially identical; the same is highly probable in regard to the powers of life : in analysing physical phenomena, however, it is found far more conve- nient to consider the powers above mentioned separately, and it cannot be doubted that physiologists would derive equal advantage from pursuing a similar method. Accord- ing to the author’s representation, the modifications of life result simply from differences in the organized apparatus, through which it manifests its effects, nearly in the same way as mechanical force may be made to produce the most different effects, according to the kind of machinery which is-employed.]](https://iiif.wellcomecollection.org/image/b21996623_0001_0253.jp2/full/800%2C/0/default.jpg)
