unconsciously and slowly, but more efficiently, seems to have been the predominant Power."*

If thus the variations of floral structures can be reasonably referred directly to external agencies, and we may speak of each as a cause instead of using the abstract expresssion “natural selection," there still remains the question, What has brought into existence the primary flowers themselves, which insects have subsequently modified into their present conditions?

THE ORIGIN OF FLOWERS.-There are good reasons for regarding Gymnosperms-both from their extreme antiquity, as well as from points of structure showing affinity with the higher Cryptogams; such, for example, as the Lycopodiaceœ-as standing in some sort of way intermediate between the latter and Dicotyledons. Yet the connecting links are much wanted on both sides of them. As far as Coniferæ and Cycadeæ can help us, we are strongly led to believe that they were primitively, just as they are now, anemophilous and diclinous; though the subdioecious (?) Welwitschia has points of structure which seem to indicate its being a degraded state of an hermaphrodite plant. This remarkable monotypic genus is, however, too isolated and unique to afford any safe point of departure on the road to Dicotyledons, so that with regard to the latter we are still driven to speculation alone.

If, then, we are right in assuming Gymnosperms to have been always diclinous, and Dicotyledons to have arisen from some member of that group, then it is presumable that the first were diclinous, perhaps dioecious, and anemophilous as well. The general opinion seems to be that they were diœcious; and Mr. Darwin thought that monoecism was the next step, and thence hermaphroditism was ultimately reached.

*Origin of Species, 6th ed., p. 31.

Z

Now, we must not forget that when a female flower is pollinated the effect of the impregnation by the pollen-tube is not only to create an embryo in the ovule, but to endow it potentially with its own sexuality; so that the sexless embryo becomes potentially both male and female; in as much as it may subsequently grow up to be solely a male or solely a female plant; or else it may combine the sexes, either as a monoecious or hermaphrodite plant.

Moreover, we now know that the resulting sex which appears in dioecious plants on maturity is largely, if not entirely, dependent upon conditions of nutrition, possibly aided by other and unknown influences.

Consequently, we cannot say for certain whether the first Dicotyledons were not at least monoecious, if not hermaphrodite, since the former of these states prevails already in Gymnosperms, as in Pinus; while the latter is hinted at in not infrequent monstrous conditions when the lowermost scales of the spiral series in cones of Abies excelsa, etc., are antheriferous, instead of being ovuliferous. * Such cases show that one (the male) sex can suddenly appear in the same spiral series as the other. And this is all that is wanted to form an hermaphrodite flower; for continuously spirally-arranged sexual organs are characteristic of many plants, such as of the Ranunculaceœ; and such a monstrous condition may simply be a reversion to a primitive hermaphrodite state. Hence appears the inherent possibility of the production of hermaphroditism without any slow evolutionary process at all; but simply as a result of the conveyance of the male energy to the female plant, by the very act of pollination itself.

Mr. Darwin, when speculating on the origin of hermaphroditism, wrote as follows: "By what graduated steps *Teratology, p. 192.

an hermaphrodite condition was acquired we do not know. But we can see that if a lowly organised form, in which the two sexes were represented by somewhat different individuals, were to increase by budding either before or after conjugation, the two incipient sexes would be capable of appearing by buds on the same stock, as occasionally occurs with various characters at the present day. The organism would then be in a monoecious condition, and this is probably the first step towards hermaphroditism; for if very simple male and female flowers on the same stock, each consisting of a single stamen or pistil, were brought close together and surrounded by a common envelope, in nearly the same manner as with the florets of the Composite, we should have a hermaphrodite flower." *

It is a singular fact that Mr. Darwin never seems to have thought of Euphorbia, which tallies exactly with his hypothetical origin of a hermaphrodite flower; but, unfortunately, a "blossom" of an Euphorbia is not regarded by botanists as a flower, but an inflorescence. It consists of a "single pistil," on its own pedicel, surrounded by many "single stamens," each on their own pedicels; and are "brought close together and surrounded by a common envelope."

Mr. Darwin's mistake resides in his supposition that hermaphroditism must have arisen from diœcism, by passing through monœcism; so that he is obliged by this order of progress to consider a flower with stamens and a pistil to be made of separate flower-buds, i.e. to be axial structures with their appendages reduced to at least one of each kind. from phyllotactical reasons, it is clear that the origin and arrangements of the floral members are entirely foliar.

But

All that seems necessary for us to assume as the origin of a flower with a conspicuous corolla or perianth, is a leaf-bud Cross and Self Fertilisation of Plants, p. 410.

of which some of the members have already differentiated into carpellary, others into staminal organs, the outer appendages being simply bracts, like, we will say, those surrounding the stamens or ovule of the Yew.

As insects often come for pollen alone-as in honeyless flowers of Laburnum, Poppies, St. John's Wort, and Roses,— and then pierce the juicy tissues for moistening the honey, as they have been seen to do in Anemone, Laburnum, Hyacinths, Orchis, etc., we may, I think, infer with some probability that they did the same with the primitive flowers.

Having once attracted insects to come regularly, then a multitudinous series of differentiations would follow. The corolla would in all probability be the first to issue out of the bracts, as being the next whorl to the stamens and as a result of stimulus; other changes, already described under the Principles of Variation, would follow by degrees and in different combinations; but in every case they would be due to the responsive action of the protoplasm in consequence of the irritations set up by the weights, pressures, thrusts, tensions, etc., of the insect visitors.

Thus, then, do I believe that the whole Floral World has arisen.

INDEX.