Page:Mind (New Series) Volume 9.djvu/340

 326 CHAELES S. MYEBS : Given a protoplasmic molecule whose huge unstable structure contains numerous asymmetric carbon-atoms, this molecule may conceivably be ever adding to itself from the external media and be forming a still more complex and unstable molecule, pari passu with the increasing number of asym- metric atoms. At length, however, division of the molecule must come about, and two new molecules are formed ; that is to say, the protoplasm has undergone metabolism. The nature of the intra-molecular division will be largely de- termined by external conditions ; in other words, living substance necessarily adapts itself to its environment. Unfortunately the present state of physiological chemistry is too feeble to sustain so fascinating a hypothesis. Hitherto the chemical examination of protoplasm has signally failed. All that has been studied is a collection of substances of various complexity, yielded by the breaking down of proto- plasm. It is now well known that the chemistry of dead matter is very different from that of living matter, and the reason once preferred by Miiller for the introduction of a vital principle (p. 24) is no longer adequate. Moreover, the synthesis of urea by Wohler in 1828 and the subsequent researches of Liebig and his successors have completely overthrown the old idea of "organic" chemistry. It is perhaps not going too far to expect in the near future a synthesis of albumen, and in this connexion it is suggestive that optically-active sugars have been prepared from the reduction of certain proteids. Yet hitherto the chemistry of living substance itself remains untouched. " Protoplasm '' is a word devoid of chemical significance, useful, like its daughter term "Enzyme," to connote certain obscure re- actions rather than to denote any definite substance. 1 The physical constitution of protoplasm is as little known as the chemical. By some, e.g., W. Fleming, it has been called a feltwork ; by others, e.g., Fr. Leydig, a spongework. Biitschli (25), from his researches into the protoplasmic-like movements of delicately foaming emulsions of olive-oil, has concluded that protoplasm has a lamellar honeycomb-struc- ture. The granula theory of Altmann, partly descriptive, partly hypothetical, bridges across the gulf that divides the above microscopically-derived contentions from such purely imaginary creations as the micellae of Nageli, the tagmata of Pfeiffer, the bioplasts of Pfluger, pangenae of De Vries, the 1 Recent experiments on the wonderful resistance of seeds to extra- ordinarily low temperatures can surely only be interpreted by the supposition that a wide difference exists between the chemistry of a seed and that of its seedling.