part." Shall we ascribe a "vital principle" to the unorganized crystal as well as to the organized vegetable or animal tissue?
The mysteries of nature are not all confined to life-expressions. Who shall explain the ultimate nature of crystallization, which, under the laws of fixed axial ratios, gives to each variety such definite and invariable form? Who shall explain the flower's perfume? Where is the "vital force" in the seed which lies for ages in the tomb of some Pharaoh? Does "vital force," as an independent entity, which works contrary to physical and chemical laws, thus imprison itself and voluntarily submit to what must be, to it, a death? If it acts independently of the physical forces of nature, why has it not furnished evidence thereof in some way or at some time? How is life made active in this seed so long dried and practically dead? Not by any occult influence at discord with organic growth, but simply by environing the seed with conditions favorable to physical well-being. Heat, light, and moisture all physical and chemical agents soon revivify this seed, and evidence is added to sustain the proposition that, while "the present state of knowledge furnishes us with no link between the living and the not-living," yet are both actuated by forces of the same kind. "Vital force," therefore, is, in reality, only another term for the properties of matter; it denotes simply the causes of certain great groups of natural operations, as we employ the terms "electricity" and "electrical force" to denote others. But to use the term "vitality" or "vital force" in the sense of an entity, which acts as an efficient cause of vital phenomena, is an assumption as absurd as to assume that "'electric,' 'attractive,' and 'chemical' forces are entities which determine the phenomena of electricity, chemism, and gravitation."
"If we knew all the laws of the composition of matter, and all the changes of which it is capable, every phenomenon which any given substance presents must be caused either by something taking place in the substance or by something taking place out of it, but acting upon it. Those mysterious forces, whether they be emanations from matter or whether they be merely properties of matter, must, in an ultimate analysis, depend either on the internal arrangement or on the external locality of their physical antecedents. However convenient, therefore, it may be, in the present state of our knowledge, to speak of vital principles, imponderable fluids, and elastic ethers, such terms can only be provisional, and are to be considered as mere names for that residue of unexplained facts which it will be the business of future ages to bring under generalizations wide enough to cover and include the whole."
As mechanical energy manifests different powers and results as it operates through differently constructed mechanisms, so vital energy becomes more complex in its manifestations as the organism through which its work is displayed is more complicated in structure.
Jevons has well defined the physiological significance of "vital
