"I could prove that it is not the form either of the body or of its parts which gives rise to habits, to the mode of life of animals, but, on the contrary, it is the habits, the mode of life, and all the influential circumstances which have, with time, made up the form of the body and of the parts of animals. With the new forms new faculties have been acquired, and gradually nature has reached the state in which we actually see her" (pp. 12-15). He then points out the gradation which exists from the most simple animal up to the most composite, since from the monad, which, so to speak, is only an animated point, up to the mammals, and from them up to man, there is evidently a shaded gradation in the structure of all the animals. So also among the plants there is a graduated series from the simplest, such as _Mucor viridescens_, up to the most complicated plant. But he hastens to say that by this regular gradation in the complication of the organization he does not mean to infer the existence of a linear series, with regular intervals between the species and genera: "Such a series does not exist; but I speak of a series almost regularly graduated in the principal groups (_masses_) such as the great families; series most assuredly existing, both among animals and among plants, but which, as regards genera and especially species, form in many places lateral ramifications, whose extremities offer truly isolated points." This is the first time in the history of biological science that we have stated in so scientific, broad, and modern form the essential principles of evolution. Lamarck insists that time without limit and favorable conditions are the two principal means or factors in the production of plants and animals. Under the head of favorable conditions he enumerates variations in climate, temperature, the action of the environment, the diversity of local causes, change of habits, movement, action, variation in means of living, of preservation of life, of means of defence, and varying modes of reproduction. As the result of the action of these different factors, the faculties of animals, developed and strengthened by use, become diversified by the new habits, so that by slow degrees the new structures and organs thus arising become preserved and transmitted by heredity. In this address it should be noticed that nothing is said of willing and of internal feeling, which have been so much misunderstood and ridiculed, or of the direct or indirect action of the environment. He does speak of the bird as wishing to strike the water, but this, liberally interpreted, is as much a physiological impulse as a mental desire. No reference also is made to geographical isolation, a factor which he afterwards briefly mentioned. Although Lamarck does not mention the principle of selection, he refers in the following way to competition, or at least to the checks on the too rapid multiplication of the lower invertebrates: