At a later period, that of the primary and secondary rocks, there was a uniform and constant temperature of about 40deg C. The atmosphere was charged with water vapour, and all the conditions were present for the production of storms and tempests. The atmosphere during long ages must have been the seat of formidable and incessant electric discharges; these discharges are the most powerful of all physical agents of chemical synthesis, and will cause nitrogen to combine directly to form various compounds--nitrates, cyanides, and ammonia. Carbonic acid would also be present in abundance and would enter into combination with these nitrogenous compounds. In this way we may imagine that compounds were formed which by some process of physical synthesis subsequently gave rise to vast quantities of albuminoid matter. At that time the seas and oceans contained all those substances which have {170} since been fixed by the metamorphism of the primitive rocks, or deposited in the sedimentary strata. Most of the elements in our minerals were formerly in a state of solution in these primeval seas, which contained carbonates, silicates, and soluble phosphates in great abundance. As the crust gradually cooled, the terrestrial atmosphere of necessity altered in composition, and the slow evolution of the atmosphere no doubt also exercised an influence on the development of living beings. Palaeontology teaches us that the earliest living organism appeared in the sea. The most ancient of living things, those of the primary ages, which were of greater duration than all other ages put together, were all aquatic. We find moreover that every living organism consists of liquids, solutions of crystalloids and colloids separated by osmotic membranes; and it is significant that the ocean, that vast laboratory of life, is also a solution of crystalloids and colloids. It is evident, then, that we must look to the study of solutions if we would hope to discover the nature and origin of life. Life is an ensemble of functions and of energy-transformations, an ensemble which is conditioned by the form, the structure, and the composition of the living being. Life, therefore, may be said to be conditioned by form, _i.e._ the external, internal, and molecular forms of the living being.