A few writers have either ignored the presence of smaller units, or have dealt with the organism from a purely chemical and physical point of view. They attempt to account for the changes in the organism as the outcome of known physical and chemical principles. It must, of course, be granted that in a sense the properties of the organism are the result of the material basis of the organism; but in another sense this idea gives a false conception of the phenomena of life, because, if we were simply to bring together those substances that we suppose to be present in the organism we have no reason to think that they would form an organism, or show the characteristic reactions of living things. Even from a chemical point of view we can see how this result could not be expected, for it is well known that the order in which a compound is built up, _i.e._ the way in which the atoms or molecules are introduced into the structure, is an important factor in the making of the compound. When we remember the immense period of time during which the organisms living at present have been forming, we can appreciate how futile it will be to attempt to explain the behavior of the organism from the little we know in regard to its chemical composition. Its chief properties are the result of its peculiar structure, or the way in which its elements are grouped. This structure has resulted from the vast number of influences to which the organism has been subjected, and while it may be granted that if we could artificially reproduce these conditions an organism having all the properties that we associate with living things would result, yet the problem appears to be so vastly complicated that few workers would have the courage to attempt to accomplish the feat of making artificially such a structure. To prevent misunderstanding, it may be added that while from the point of view here taken, we cannot hope to explain the behavior of the organism as the resultant of the substances that we obtain from it by chemical analysis (because the organism is not simply a mixture of these substances), yet we have no reason to suppose that the organism is anything more than the expression of its physical and chemical structure. The vital phenomena are different from the non-vital phenomena only in so far as the structure of the organism is different from the structure of any other group of substances.