self-evident absurdity. It is not the cell matter alone that does make up the “_I_.” The cell matter is only so much working material of a particular kind, and a something uniquely determining this material must appear on the scene, otherwise there would offer no possibility whatever of the fact, “_I_.” To think to explain me by the cell matter alone were somewhat the same as thinking to explain the flame by the kindling wood and the oxygen of the atmosphere, exclusively. Of such an _Hebraic_ conception of the matter--to speak like Humboldt--no physicist would ever be guilty; but the biologist is. The manner in which he deals with the problem of heredity is Hebraic in the fullest sense of the word, and so fashioned that it cannot help but tumble to the ground simply of its own weight. Assuming beforehand the identity of “life” and “cell,” endeavour is made to solve the riddle of life by means of description alone, the way leading from the material of generation to the new living being plotted out with ever increasing exactitude until finally an apparently uninterrupted succession stands before us; where, to be sure, it is conveniently forgotten that its seeming continuity is solely due to the fineness, the delicacy, of the isolated momentary images. As little as I can fabricate actual, living movement out of a series of stereoscopic pictures, though making never so slight the duration of each separate picture, just as little is the process of generation to be comprehended by mere description, even though it bring before us a simply endless number of phases of development. Still, I can lull myself with the delusion that by this method I am drawing ever nearer to my goal, and that salvation lies simply in the fineness of the lenses, the delicacy and ingenuity of the modes of colouring, and in patience. But far other powers than these are required for the solving of the riddle of life. For upon this line of inquiry one remains ever and always concerned with reactions. Let the discoveries thus made, the new demonstrations of the entire process supplied, be never so novel, never so interesting, withal they remain reactions, and tell us nothing save that energies _must_ be present; never a word do they say bearing on these latter themselves.