It is interesting to note that Lamarck expressly refers to Bonnet (p. 110), but refuses to accept his view of an _Echelle_ extending down into the inorganic. Like Bonnet, however, and like the German transcendentalists, Lamarck makes man the goal of evolution (p. 116). He makes it quite clear that his _Echelle_ is a functional one, for he links Vertebrates to molluscs even while expressly admitting that they are not connected by any structural intermediates (p. 123). He does not fall into the error of the transcendentalists and assume that Vertebrates and Invertebrates alike are formed upon one common plan of structure. The progression of organisation shown by the animal kingdom has not been altogether regular and uninterrupted:--"The progression in complexity of organisation shows here and there, in the general animal series, anomalies induced by the influence of environment and by the influence of the habits contracted" (_Phil. zool._, i., p. 145). There are thus really two causes at work to produce the variety of organisation as it appears to us, one which tends to produce a regular increase in complexity, and one which disturbs and diversifies this regular advance. The first cause Lamarck calls the vital power (_pouvoir de la vie_); the other may be called the influence of circumstance (_Anim. s. Vert._, p. 134). To the latter cause are due the lacunae, the blind alleys, and the complications which the otherwise simple scale of perfection shows. To explain both these aspects of evolution Lamarck propounded in his volume of 1816 four laws, which read as follows:-- "_First Law_.--Life, by its own forces, tends continually to increase the volume of every body possessing it, and to extend the dimensions of its parts, up to a limit which it brings about itself. "_Second Law_.--The production of a new organ in an animal body results from the arisal and continuance of a new need, and from the new movement which this need brings into being and sustains. "_Third Law_.--The degree of development of organs and their force of action are always proportionate to the use made of these organs. "_Fourth Law_.--All that has been acquired, imprinted or changed in the organisation of the individual during the course of its life is preserved by generation and transmitted to the new individuals that descend from the individual so modified" (pp. 151-2). It is mainly but not entirely by reason of the first of these laws that organisation tends to progress, and mainly by reason of the second and third that difference of environment brings about diversity of organisation. In virtue of the fourth law the acquirements of the individual become the property of the race.