and systematic importance. The compounding these two applications of the word is apt to lead into some fallacies. De Candolle, for instance, after showing the impossibility of establishing any comparison of relative importance in the functions of the organs of reproduction and those of vegetation, but explaining why it is that the former practically supply better characters than the latter, lays down the following scale of progression in the importance of these reproductive organs:—
1. L'embryon qui est le but de tout;
2. Les organes sexuels, qui en sont le moyen;
3. Les enveloppes de l'embryon;
4. Les enveloppes des organes sexuels;
5. Les nectaires ou organes accessoires.
But, in the first place, the embryo in its perfect state can no longer be called an organ of the parent plant. Until it is fully formed, it supplies no characters. When once formed, it has no function to perform till it commences life as a new independent being. And this is the great reason of the importance of the characters it then supplies. It is a whole plant, not an organ of a plant.
Secondly, the same arguments which show the impossibility of comparing the importance of the functions of the reproductive and vegetative organs, would apply to the flower (or 'les organes sexuels') and the fruit (comprised in 'les enveloppes de l'embryon')—the apparatus for producing the embryo and the apparatus for bringing it to perfection—and, again, in the flower, between the male and the female organs; for all these are equally essential for completing the series of vital phenomena which continue the species. It is true that, exceptionally, embryos may be formed and brought to perfection without normal fertilisation, but so also the whole series may be dispensed with, and plants are reproduced by buds without passing through the embryo state; but in all phanerogamic species, for their normal reproduction, the whole series, the male organs, the female organs, and the organs of maturation, are equally essential.
Perhaps all that can be said of the relative importance of organs with reference to their functions is this: That the so-called essential organs, the sexual organs, and the organs of maturation among the reproductive, and the perfect leaves or foliaceous surfaces, and the root-fibres among the nutritive, stand first; the protective organs, such as floral and fruit envelopes, bud-scales, &c., occupy the second rank; and accessory organs, including epidermal scales, are the lowest. But here again the relative importance of these organs is not proved by à priori arguments, derived from the necessity of their presence for performing those functions, but from the observation of the degree of constancy of their being so employed. Cryptogamic plants have sometimes none, sometimes not all, of the organs of the first degree; yet nutrition, fertilisation, and reproduction, take place, but by other means, with another class of organs. And had we observed that, in phanerogamous plants, fertilisation of the ovule never took place unless the sexual organs were enclosed in floral
