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And that stigmatic title of long standing, more than anything earthly, drove him to the step-to the ruin of his domestic felicity perhaps. But we are past sighing. 'Think you, when he crossed the tide, Caius Julius Caesar sighed? 'No, nor thought of his life, nor his wife, but of the thing to be done. Laugh, my boy! I know what I am about when I set my mind on a powerful example.
In many cases this is assured by the pollen-bearing flowers and stigmatic flowers being entirely distinct, as in cucumbers and Indian-corn; perhaps on different plants, as in the palms and willows; again by the pollen maturing and disseminating before the stigma is mature, as already mentioned, and vice versa.
There must sometimes be a physical impossibility in the male element reaching the ovule, as would be the case with a plant having a pistil too long for the pollen-tubes to reach the ovarium. It has also been observed that when the pollen of one species is placed on the stigma of a distantly allied species, though the pollen-tubes protrude, they do not penetrate the stigmatic surface.
So it is with the reciprocally dimorphic and trimorphic plants previously alluded to. How strange are these facts! How strange that the pollen and stigmatic surface of the same flower, though placed so close together, as if for the very purpose of self-fertilisation, should be in so many cases mutually useless to each other!
On this jacket we distinguish three pairs of tiny legs, reduced to short vestiges, to stumps. The head is in place, showing quite perceptibly the fine mandibles and the other parts of the mouth. There is no trace of eyes. Each side has a white edging of shrivelled tracheæ, running from one stigmatic orifice to another.
It will be seen that only the outer side of this appendage is stigmatic, and that it is thus naturally impossible for the blue-flag to self-fertilize only one instance of thousands in which the anther and stigma, though placed in the closest proximity, and apparently even in contact seemingly with the design of self-fertilization are actually more perfectly separated functionally than if in separate flowers, the insect alone consummating their affinity.
Its descendants would probably inherit a tendency to a similar slight deviation of structure. Thus it might be a great advantage to the hive-bee to have a slightly longer or differently constructed proboscis. On the other hand, I have found by experiment that the fertility of clover depends on bees visiting and moving parts of the corolla, so as to push the pollen on to the stigmatic surface.
Cookson's enthusiasm simultaneously. He did not yet know, and, happily, these experiments gave him no reason to suspect, that pseudo-fertilization can be produced, actually, by anything. So intensely susceptible is the stigmatic surface of the Cypriped that a touch excites it furiously.
In the next stage the anthers have withered, the flower-tube elongated, and the top of the two-parted pistil begins to protrude, and at length expands its tips, disclosing at the centre the stigmatic surface, which has until now been protected by close contact. The ring of pollen is inevitably scattered to the stigmas of the neighboring flowers, and cross-fertilization continually insured.
In some flowers this separation is effected, as I have shown, by their maturing at different periods; in others, as in the iris, by mere mechanical means; while in a long list of plants, as in the willow, poplar, hemp, oak, and nettle, the cross-fertilization is absolutely necessitated by the fact of the staminate and stigmatic flowers being either separated on the same stalk or on different plants, the pollen being carried by insects or the wind.
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