It cannot be surprising that those who believe {81} the door to be shut, so to speak, in the direction of any theory of development through mechanical and chemical agencies alone, should look elsewhere for the solution of a problem which science is bound to do its very utmost to solve. This is what, as a matter of fact, is happening; and it is of the very deepest interest to observe the nature of the suggested explanation. It is no other than a revived form of the ancient doctrine of a "vital force," which we had imagined to have been finally discarded. There is this difference, however, and it is all-important. The force is not, as formerly supposed, some unique kind of energy; is not, indeed, energy at all. But we shall do best to state the new doctrine in the words of its leading exponents. Professor Anton Kerner, one of the most distinguished German writers on Botany, in his _Natural History of Plants_, speaking of the chemical explanation, says: "It does not explain the purposeful sequence of different operations in the same protoplasm without any change in the external stimuli; the thorough use made of external advantages; the resistance to injurious influences; the avoidance or encompassing of insuperable obstacles; the punctuality with which all the functions are performed; the periodicity which occurs with the greatest regularity under constant conditions of environment; {82} nor, above all, the fact that the power of discharging all the operations requisite for growth, nutrition, renovation and multiplication is liable to be lost." And then he gives his opinion thus: "I do not hesitate again to designate as vital force this natural agency, not to be identified with any other, whose immediate instrument is the protoplasm, and whose peculiar effects we call life." Sir Oliver Lodge is, perhaps, the most uncompromising advocate of the newer vitalism in England. The following striking quotations will set forth his views: Life, he maintains, is no more a function of matter "than the wind is a function of the leaves which dance under its influence."[8] "If it were true that vital energy turned into, or was anyhow convertible into, inorganic energy, if it were true that a dead body had more inorganic energy than a live one, if it were true that 'these inorganic energies' always, or ever, 'reappear on the dissolution of life,' then, undoubtedly, _cadit quaestio_, life would immediately be proved to be a form of energy, and would enter into the scheme of physics. But, inasmuch as all this is untrue--the direct contrary of the truth--I maintain that life is not a form of {83} energy, that it is not included in our present physical categories, that its explanation is still to seek." "It appears to me to belong to a separate order of existence, which interacts with this material frame of things, and, while there, exerts guidance and control on the energy which already exists."[9]