ãmodes of packingã or of ãspace-latticesã remain as useful as ever for the definition and explanation of the molecular arrangements, an entirely new theoretical conception is introduced when we find such space-lattices maintained in what has hitherto been considered the molecular freedom of a liquid field; and we are constrained, accordingly, to postulate a specific molecular force, or ãGestaltungskraftã (not unlike Keplerãs ãfacultas formatrixã), to account for the phenomenon.
Now just as some sort of specific ãGestaltungskraftã had been of old the deus ex machina accounting for all crystalline phenomena (gnara totius geometriûÎ, et in ea exercita, as Kepler said), and as such an hypothesis, after being dethroned and repudiated, has now fought its way back and has made good its right to be heard, so it may be also in biology. We begin by an easy and general assumption of specific properties, by which each organism assumes its own specific form; we learn later (as it is the purpose of this book to shew) that throughout the whole range of organic morphology there are innumerable phenomena of form which are not peculiar to living things, but which are more or less simple manifestations of ordinary physical law. But every now and then we come to certain deep-seated signs of protoplasmic symmetry or polarisation, which seem to lie beyond the reach of the ordinary physical forces. It by no means follows that the forces in question are not essentially physical forces, more obscure and less familiar to us than the rest; and this would seem to be the crucial lesson for us to draw from Lehmannãs surprising and most beautiful discovery. For Lehmann seems actually to have demonstrated, in non-living, chemical bodies, the existence of just such a determinant, just such a ãGestaltungskraft,ã as would be of infinite help to us if we might postulate it for the explanation (for instance) of our Radiolarianãs axial symmetry. But further than this we cannot go; for such analogy as we seem to see in the Lehmann phenomenon soon evades us, and refuses to be pressed home. Not only is it the case, as we have already {487} seen, that certain of the geometric forms assumed by the symmetrical Radiolarian shells are just such as the ãspace-latticeã theory would seem to be inapplicable to, but it is in other ways obvious that symmetry of cryôÙstalôÙliôÙsaôÙtion, whether liquid or solid, has no close parallel, but only a series of analogies, in the protoplasmic symmetry of the living cell.