In October, 1858, he published in the Medico-Chirurgical Review a criticism on Prof. Owen's "Archetype and Homologies of the Vertebrate Skeleton," which was written in furtherance of the doctrine of Evolution, and to show that the structural peculiarities which are not accounted for on the theory of an archetypal vertebra, are accounted for on the hypothesis of development. In January of the next year, there appeared in the same review a paper on "The Laws of Organic Form," already referred to, the germ of which dated back to 1851, and which was a further elucidation of the doctrine of Evolution, by showing the direct action of incident forces in modifying the forms of organisms and their parts. In April, 1859, appeared in the British Quarterly Review an article on "Physical Education," in which the bearing of biological principles upon the management of children in respect to their bodily development is considered. It insists upon the normal course of unfolding, versus those hindrances to it which ordinary school regulations impose; it asserts the worth of the bodily appetites and impulses in children, which are commonly so much thwarted; and contends that during this earlier portion of life, in which the main thing to be done is to grow and develop, our educational system is too exacting—"it makes the juvenile life far more like the adult life than it should be." The essay "What Knowledge is of most Worth" was printed in the Westminster Review for July, 1859. This argument is familiar to the public, as it has been many times republished, but what is here most worthy of note is that, in criticising the current study of history, it defines with great distinctness the plan of the "Descriptive Sociology," the first divisions of which are now just published, and form the comprehensive and systematic data upon which the Principles of Sociology are to be based.
An argument on "Illogical Geology" was contributed in July, 1859, to the Universal Review, which, although nominally a criticism of Hugh Miller, was really an attack upon the prevalent geological doctrine which asserted simultaneity in the systems of strata in different parts of the earth. His view, which was at that time heresy, is now coming into general recognition. In the Medico-Chirurgical Review for January, 1860, Mr. Spencer published a criticism on Prof. Bain's work, "The Emotions and the Will," designed to show that the emotions cannot be properly understood and classified without studying them from the point of view of Evolution, and tracing them up through their increasing complications from lower types of animals to higher. The essay on the "Social Organism" appeared at the same time in the Westminster Review, in which it was maintained that society, consisting of an organized aggregate, follows the same course of Evolution with all other organized aggregates—increasing in mass and showing a higher integration not only in this respect but also in its growing solidarity; becoming more and more heterogeneous in all its structures and more and more definite in all its differentiations. The