Still more important is the bridging over the supposed gulf between the inorganic and the organic chemical substances. A few years back this gulf was supposed to be great, fixed, impassable. The mineral or inorganic was makable by man. The organic was not, and never would be. The chemist might go on continually manufacturing hydrogen and oxygen, carbon dioxide, ammonia. But he was never to hope to make alcohol, sugar, urea, any of the multitudinous substances called organic. And now all this folly of forbidding is at an end. The organic bodies are manufactured by man. The inorganic and the organic are no more regarded as clearly distinguishable. Even the chemistry books by their very titles recognise and proclaim this fact. We have no longer works on organic chemistry. We have volumes on the chemistry of carbon compounds. In geology the different kinds of rocks graduate into each other. Between the aqueous, or sedimentary, and the igneous, or those due to the action of fire, range the metamorphic, i.e., sedimentary rocks that have been afterwards subjected to heat. The various systems of sedimentary rocks are known now to be purely artificial if convenient divisions. From the Laurentian up to the recent rocks there has never been any real hiatus. Nowhere is there the slightest evidence of pause or of recommencement. Our groups are artificial. Nature is like Oallio and cares for none of these things. Whilst rocks thus glide one into the other, the fossil remains that they contain do likewise. If the view of the special creationist were accurate we ought to find isolated forms of dead animals and plants, we ought to find sudden appearances in the rocks of forms not allied to these already encountered, we ought not necessarily to find a series of organic remains ascending in complexity of structure. If the view of the evolutionist is accurate, we ought to find no forms of dead animals or plants isolated; we ought never to find a form appearing without preliminary heralds of its coming in the shape of kindred forms; we ought to find a series of organic remains whose later members are in advance of the earlier. These latter expectations are realised. In like manner the gap supposed to exist between the kingdoms of the non-living and living is closing up. As long as men had only studied the higher forms of living things there was no difficulty in defining and distinguishing living organisms. To define and to distinguish the lowest forms of those now known is impossible. How completely this is true can only be understood by those who have studied the protoplasmic masses that hover on the border line between the organic and the inorganic. But even the unskilled in microscopic work will be able to grasp something of the great truth if they will take the trouble to look up the innumerable definitions of life that have been given by various persons, and note how unsatisfactory, how contradictory and often self-contradictory they are.