For the rest, it cannot even be said that the palæontological record furnishes good circumstantial evidence that our globe has been the scene of a process of organic evolution. In fact, so utterly at variance with this view is the total impression conveyed by the visible portion of the geological column, that the modern geologist proposes, as we have seen, to probe depths beneath its lowest strata for traces of that alleged transmutation, which higher horizons do not reveal. There are six to eight thick terranes below the Cambrian, we are told, and igneous masses that were formerly supposed to be basal have turned out to be intrusions into sedimentary accumulations, all of which, of course, is fortunate for the theory of organic evolution, as furnishing it with a sadly needed new court of appeal. The bottom, so to speak, has dropped out of the geological column, and Prof. T. C. Chamberlin announces the fact as follows: “The sharp division into two parts, a lifeless igneous base and a sedimentary fossiliferous superstructure, has given place to the general concept of continuity with merely minor oscillations in times and regions of major activity. Life has been traced much below the Cambrian, but its record is very imperfect. The recent discoveries of more ample and varied life in the lower Palæozoic, particularly the Cambrian, implies, under current evolutional philosophy, a very great downward extension of life. In the judgment of some biologists and geologists, this extension probably reaches below all the pre-Cambrian terranes as yet recognized, though this pre-Cambrian extension is great. The ‘Azoic’ bottom has retired to depths unknown. This profoundly changes the life aspect of the ‘column.’” (_Science_, Feb. 8, 1924, p. 128.) All this is doubtless true, but such an appeal, from the known to the unknown, from the actual to the possible, is not far-removed from a confession of scientific insolvency. Life must, of course, have had an earlier history than that recorded in the pre-Cambrian rocks. But even supposing that some portion of an earlier record should become accessible to us, it could not be expected to throw much light on the problem of organic origins. Most of the primordial sediments have long since been sapped and engulfed by fiery magmas, while terranes less deep have, in all probability, been so metamorphosed that every trace of their fossil contents has perished. The sub-Archæan beginnings of life will thus remain shrouded forever in a mystery, which we have no prospect of penetrating. Hence it is the exposed portion of the geological column which continues and will continue to be our sole source of information, and it is preëminently on this basis that the evolutionary issue will have to be decided.