of Species] is a protracted argument intended to prove that the species we recognize have not been independently created as such, but have descended, like varieties, from other species. Varieties, on this view, are incipient or possible species; species are varieties of a larger growth, and a wider and earlier divergence from the parent stalk; the difference is one of degree, and not of kind."1 "In applying his principle of natural selection to the work in hand, Mr. Darwin assumes, as we have seen: (1) Some variability of animals and plants in nature; (2) the absence of any definite distinction between slight variations and varieties of the highest grade; (3) the fact that naturalists do not practically agree, and do not increasingly tend to agree, as to what forms are species and what are strong varieties, thus rendering it probable that there may be no essential and original difference, or no possibility of ascertaining it, at least in many cases; also (4) that the most flourishing and dominant species of the larger genera on an average vary most (a proposition which can be substantiated only by extensive comparisons, the details of which are not given); and (5) that in large genera the species are apt to be closely but unequally allied together, forming little clusters round certain species—just such clusters as would be formed if we suppose their members once to have been satellites or varieties of a central or parent species, but to have attained at length a wider divergence and a specific character. The fact of such association is undeniable; and the use which Mr. Darwin makes of it seems fair and natural.

"The gist of Mr. Darwin's work is to show that such varieties are gradually diverged into species and genera through natural selection; that natural selection is the inevitable result of the struggle for existence which all living things are engaged in; and that this struggle is an unavoidable consequence of several natural causes, but mainly of the high rate at which all organic beings tend to increase." 2

Returning for a moment to De Candolle's article, we are disposed to notice his criticism of Linnæus's 'definition' of the term species (Philosophia Botanica, No. 157): 'Species tot numeramus quot diversae formae in principio sunt creatae' - which he

1 Darwiniana, p. 11.

2 Ibid., p. 36.

declares illogical, inapplicable, and the worst that has been propounded. So, to determine if a form is specific, it is necessary to go back to its origin, which is impossible. A definition by a character which can never be verified is no definition at all.'

"Now, as Linnæus practically applied the idea of species with a sagacity which has never been surpassed, and rarely equaled, and, indeed, may be said to have fixed its received meaning in natural history, it may well be inferred that in the phrase above cited he did not so much undertake to frame a logical definition, as to set forth the idea which, in his opinion, lay at the foundation of species; on which basis A. L. Jussieu did construct a logical definition 'Nunc rectius definitur perennis individuorum similium successio continuata generatione renascentium.' The fundamental idea of species, we would still maintain, is that of a chain of which genetically connected individuals are the links. That, in the practical recognition of species, the essential characteristic has to be inferred, is no great objection - the general fact that like engenders like being an induction from a vast number of instances, and the only assumption being that of the uniformity of Nature. The idea of gravitation, that of the atomic constitution of matter, and the like, equally have to be verified inferentially. If we still hold to the idea of Linnæus, and of Agassiz, that existing species were created independently and essentially all at once at the beginning of the present era, we could not better the propositions of Linnæus and of Jussieu. If, on the other hand, the time has come in which we may accept, with De Candolle, their successive origination, at the commencement of the present era or before, and even by derivation from other forms, then the 'in principio' of Linnæus will refer to that time, whenever it was, and his proposition be as sound and wise as ever."1

". . . Species, as I have said (in Silliman's Journal articles) are not facts or things, but judgments, and, of course, fallible judgments. How fallible, the working naturalist knows and feels more than any one else." 2

Inductive Classification is the orderly arrangement of things in their natural groups or kinds. We may 1 Darwiniana, p. 201. 2 Letters, p. 657.

classify mental states or social movements, as well as physical forces and material objects, minerals, plants, and animals.

Nomenclature is a system of names for the various things classified. In Botany the name of a plant is always in Latin, and consists of the name of the genus, followed by the name of the species, as Viola blanda, sweet white violet. Unfortunately, no one has yet thought of any way of forming botanical names from natural characteristics, so that the nomenclature, also, may be natural.

On the contrary, the names of genera and species have been assigned by discoverers for trivial and often ridiculous reasons, and the whole scientific world has been forced to perpetuate the memory of silly caprices. This is an ignominy which no disciplined mind can think of without indignation. In Chemistry the names of substances are compounded of those of their elements, with prefixes and terminations suggesting their proportions. Chemical nomenclature is the best we have, but its development has lagged behind the general progress of the science. Mineralogy needs nothing more than an adequate nomenclature. system of names suggesting both crystallography and chemical composition would be far preferable to smithite, jonesite, and brownite.

A

Terminology is the precise vocabulary used in describing the parts, qualities, and actions of the objects of science. Botany has a wonderfully copious vocabulary. This vocabulary is strictly inductive; the meaning of each word is fixed by direct examination of typical specimens. Such words as serrate, dentate, crenate, runcinate, bipinnatifid, etc., are defined by exhibiting

to the learner the parts of plants which they describe, and each is ever afterwards used in precisely the same sense. By the use of a proper terminology, scientists can convey to one another, in a few words, accurate descriptions of phenomena, which pages of popular phraseology would leave still obscure.

CHAPTER IX.

FACTS OF CAUSATION AND FACTS OF

SUCCESSION.

It is a matter of observation that things in this universe react upon one another. It is further observed that after such reactions the things sometimes appear in new forms. This property of reacting, or of presenting new forms, is called the power of Causation. The several reactions of things are called events. The things which react are said to be the causes of these events. If things appear in new forms, they are said to be, in their antecedent forms, the causes of themselves in their subsequent forms.

This power of affecting, or being affected, is an ultimate property of things. It is one of those ultimate properties the coexistence of which constitutes the existing order. Science never attempts the explanation of ultimate properties; or rather, when science finds anything inexplicable she calls it ultimate.

Things exist in space, and events occur in time. Time is marked and estimated by the succession of events. And these events are seen to have often a certain relation to one another. Just as there are certain uniform coexistences of phenomena, so there are certain uniform successions. Yellowness and ductility present themselves simultaneously in gold; contact with red-hot iron and pain in the flesh present them