A few words must be added as to the teleological implications which a _Westminster_ reviewer has discovered in our previous works, and has regarded as vitiating the whole of their reasoning. The subject of teleology is a very interesting and puzzling one, and is bound to receive careful attention from the student of nature. It requires much consideration as to what is meant by the term. There may be a natural teleology apart from a supernatural teleology. We have no very clear conceptions upon this point ourselves as yet, but are at present engaged upon the study of the question. Intention and design are exemplified in human actions, means to an end are adopted by many animals; the "Moving Equilibrium" theory, and the "Happy Accident" theory alike seem inadequate to account for the origin of natural teleology or even for all variations of species; and the study of biological developments suggests to us the presence and activity of a subjective factor related to physical factors by some law to which may be due the origin of some of the biological variations. Mr. Spencer's theory of biological variations as internal forces generated by external forces, and thus acting as a counterbalance in opposition to an inimical force, or in harmony with a favourable force, having for its object the protection or sustentation of the organism, is an altogether different theory from the agnostic "Happy Accident" hypothesis of the naturalist school. It implies the origin of biological variations as means adapted to ends in the preservation of the organism or species, and if this is not found workable on the physical equilibration hypothesis, some extension of theory is required to account for the origin of biological variations in which teleological implications are involved, although this theory may be truly naturalistic and in perfect harmony with an orderly development in the manner of evolution. If we cannot predicate an anthropomorphic teleological mind at the beginning of things, nevertheless a teleology appears to be involved in biological developments and requires a naturalistic explanation.