Can the development of an organism from an egg be explained as the operation of a machine?

Although we are not yet able to state how life originated in general, another, more modest problem, has been solved, that is, how the egg is caused by the sperm to develop into a new individual. Every animal originates from an egg and in the majority of animals a new individual can only then develop if a male sex-cell, a spermatozoon, enters into the egg. The question as to how a spermatozoon can cause an egg to develop into a new individual was twelve years ago still shrouded in that mystery which today surrounds the origin of life in general. But today we are able to state that the problem of the activation of the egg is for the most part reduced to physico-chemical terms.

That there is no such thing in nature, as pre-existing organized germs: but that the unorganized matter of generation, after being duly prepared, and having arrived at its place of destination takes on a particular action, or nisus, which nisus continues to act through the whole life of the animal, and that by it the first form of the animal, or plant is not only determined, but afterwards preserved, and when deranged, is again restored. A nisus, which seems therefore to depend on the powers of life, but which is as distinct from the other qualities of living bodies, (sensibility, irritability, and contractility) as from the common properties of dead matter: that it is the chief principle of generation, growth, nutrition, and reproduction, and that to distinguish it from all others, it may be denominated the Formative Nisus (Bildungstrieb, or Nisus formativus).

Only a product of such a kind can be called a _natural purpose_, and this because it is an _organised_ and _self-organising being_. In a watch one part is the instrument for moving the other parts, but the wheel is not the effective cause of the production of the others; no doubt one part is for the sake of the others, but it does not exist by their means. In this case the producing cause of the parts and of their form is not contained in the nature (of the material), but is external to it in a being which can produce effects according to Ideas of a whole possible by means of its causality. Hence a watch wheel does not produce other wheels, still less does one watch produce other watches, utilising (organising) foreign material for that purpose; hence it does not replace of itself parts of which it has been deprived, nor does it make good what is lacking in a first formation by the addition of the missing parts, nor if it has gone out of order does it repair itself--all of which, on the contrary, we may expect from organised nature.--An organised being is then not a mere machine, for that has merely _moving_ power, but it possesses in itself _formative_ power of a self-propagating kind which it communicates to its materials though they have it not of themselves; it organises them, in fact, and this cannot be explained by the mere mechanical faculty of motion.

The chief result of the first main part of our lectures has been to prove that an autonomy of life phenomena exists at least in some departments of individual morphogenesis, and probably in all of them ; the real starting-point of all morphogenesis cannot be regarded as a machine, nor can the real process of differentiation, in all cases where it is based upon systems of the harmonious equipotential type. There cannot be any sort of machine in the cell from which the individual originates, because this cell, including both its protoplasm and its nucleus, has undergone a long series of divisions, all resulting in equal products, and because a machine cannot be divided and in spite of that remain what it was. There cannot be, on the other hand, any sort of machine as the real foundation of the whole of an harmonious system, including many cells and many nuclei, because the development of this system goes on normally, even if its parts are rearranged or partly removed, and because a machine would never remain what it had been in such cases.

The living body and its physiological environment form an organic whole, the parts of which cannot be under- stood in separation from one another. Our ordinary language as applied to life corresponds with these characteristics. We naturally speak of a living organism as an autonomous active whole, and think of it as such. The idea of its being a mechanism made up of separable parts, and actuated by external causes, is wholly unnatural to us, and becomes more and more unnatural the more we know about organisms. The concept we are using is radically different from any physical concept : for in conceiving what is living we do not separate between matter or structure and its activity. The structure itself is conceived as active — as alive. But the objection may be raised that this is only a loose and inaccurate mode of thinking and expression : for we know that the living substance consists of nothing but matter, though we do not yet know in what exact form the atoms or molecules are combined. This, it must be pointed out clearly, is simply to beg the whole question. It was the com- plete and hopeless failure of the material conception of a living organism that led to our present inquiry.