[3] _Taxis, nomos_ (relating to science of arrangement). [4] This statement is general; it will be modified hereafter. [5] _Phule-gennao_ (kind-making); genesis of the race. [6] This formulation of the laws of organic succession was given by me in 1860, before I knew anything of either Darwin’s or Spencer’s evolution. They were my own mode of formulating Agassiz’s views. [7] Genesis without previous life--spontaneous generation. [8] Fishes were first introduced in the later Silurian; but became dominant in the Devonian. [9] Amphibians were introduced in the Carboniferous, but true reptile not until the Permian. [10] Of course I mean downward in _social function_. Individually the scavenger may be nobler than the statesman. [11] Cope, “Science,” vol. ii, p. 274, 1883. [12] Boston Society of Natural History--anniversary memoir, 1880. Also, “American Naturalist,” June, 1882. [13] “Archives des Sciences,” vol. liv, 1875. [14] “Nature,” vol. xxxi, p. 4, 1884. [15] See abstract of Dr. Romanes’s views, “Nature,” vol. xxxiv, pp. 314, 336, 362. Also, discussions of the same by Meldola, Galton, Wallace, etc., in immediately subsequent numbers. [16] This subject is more fully treated in chapter IX, p. 240 _et seq._ [17] See an article entitled “Genesis of Sex,” “Popular Science Monthly,” 1879, vol. xvi, p. 167. [18] Mr. Wallace has recently, in his work on “Darwinism,” taken strong ground against this Darwinian factor. He thinks, for example, that sexual vigor is the cause of both the splendor of color and the pertinacity which secures the female. We see little difference in this way of putting it. Our object, however, is not to argue the question of what are true factors, but simply to give the most accepted, and, as it seems to us, also the most probable view. [19] By _reason_ I mean the faculty of dealing with the phenomena of the _inner world of consciousness and ideas_. Animals live in one world--the outer world of _sense_; man in two--the outer world of sense, like animals, but also in an inner and higher world of _ideas_. All that is characteristic of man comes of this capacity of dealing with the inner world. In default of a better word I call it reason. If any one can suggest a better word, I will gladly adopt it. [20] While all comparative anatomists agree that the lung is a diverticulum from the œsophagus, like the air-bladder of the gar-fish, some think that it is a _different_ diverticulum, which is seen first in the dipnoi. [21] Undoubtedly the true principle on which primary groups ought to be made is, _identity of general plan of structure_, or _traceableness of homology throughout_. For these groups are the great primary branches of the tree of life, and classification ought to represent degrees of genetic relationship. This was Agassiz’s principle, although he did not admit the genetic relation. This principle has been, it seems to us, too much neglected by later systematists.