other inorganic masses, and others to develop the various organic or life forms. The atoms of the ultimate molecules of both organic and inorganic bodies are identically the same. It depends entirely upon what particular combination of atoms takes place whether an organic or inorganic form is developed. The primordial life-form we have found to be simple homogeneous plasm, consisting of molecules, each of which is composed of atoms of five elements—carbon, oxygen, nitrogen, hydrogen, and sulphur, differing not one iota from the molecules of inorganic bodies, except that it acquires the special power of reproduction, by virtue of the peculiar combination of its atoms, which power is wanting in the inorganic world, whose molecules are composed of similar atoms, but in different combinations. This is the only difference between the organic, or life, world, and the inorganic, or lifeless, world—life being, as compared with unlife, but the power of reproduction. As examples of this, we may take crystals, the most perfect development of inorganic nature, and the moneron, the least perfect development of organic nature; and the difference between them is almost _nil_, certainly less than between the parents and offspring in many life-forms. The crystal molecules are composed of elementary chemical atoms, as are the moneron molecules; but the former grow by particles being deposited on particles externally, while the latter grow by particles penetrating from without, or being absorbed into the interior and becoming assimilated by the plasm, fresh molecules being evolved in the process, this special power of reproduction being generated by the peculiar combination of the atoms. This argument appears to me to be logically and scientifically sound, and disposes altogether of the notion of a break of continuity between the living and the unliving worlds, which is such a formidable difficulty to many minds. The plasm thus formed by the aggregation of life molecules gradually differentiates into protoplasm and nucleus, which together form a simple cell; and this cell partakes, by heredity, of the nature and properties of its parent form, and also, by adaptation to different circumstances surrounding its existence, acquires fresh properties, which, together with the inherited properties, it transmits to its progeny, thus evolving a still more complex form, inheriting the acquired and inherited properties of its parent, and again acquiring fresh properties; and so on, _ad infinitum_, through the various life-forms we know have been developed in the pedigree of man and animals, through Amœbæ, Synamœbæ, etc., as in the genealogy given above.