Perhaps even more remarkable than any of the foregoing, which are more or less automatic in their movements, is the truly astonishing and seemingly conscious mechanism displayed in the wild arum of Great Britain-the "lords and ladies" of the village lanes, the foreign counterpart of our well-known jack-in-the-pulpit, or Indian-turnip, with its purple-streaked canopy, and sleek "preacher" standing erect beneath it. A representation of this arum is shown in Fig. 12, and a cross section at A, properly indexed.
[Illustration: Fig. 12]
How confidently would the superficial-nay, even careful-examination of one of the old-time botanists have interpreted its structure: "How simple and perfect the structure! Observe how the anthers are placed so that pollen shall naturally fall directly on the stigmas and fertilize them!" Such would indeed appear to be intended, until it is actually discovered that the stigmas have withered when the pollen is shed-a device which, acting in association with the little ring of hairs, tells a strange story. It is not my fortune to have seen one of these singular blossoms, but from the description of the process of fertilization given in Hermann Müller's wonderful work, aided by a botanical illustration of the structure of the flower, I am readily enabled to picture the progressive stages of the mechanism.
[Illustration: Fig. 13]
In the first stage (B, Fig. 13) small flies with bodies dusted with pollen from a previous arum blossom (for insects, as a rule, remain faithful or partial to one species of flowers while it is in bloom) are entering the narrowed tube, easily passing through the drooping fringe of hairs. Nectar is secreted by the stigmas, and here the flies assemble, thus dusting them with pollen. Their appetite temporarily satisfied, the insects seek escape, but find their exit effectually barred by the intruding fringe of hairs (C). In this second stage the stigmas, having now been fertilized, have withered, at the same time exuding a fresh supply of nectar, which again attracts the flies, whereupon, as shown at D, the anthers open and discharge their pollen upon the insects. In the fourth stage (E), all the functions of the flower having now been fulfilled, the fringe of hairs withers, and the imprisoned pollen-laden flies are permitted to escape to another flower, where the beautiful scheme is again enacted.
In a paper of this kind it is of course possible only to hint at a few representative examples of floral mechanisms, but these would be indeed incomplete without a closing reference to that wonderful tribe of flowers with which the theory of cross-fertilization will ever be memorably associated. I have previously alluded to the absolute dependence of the red clover upon the bumblebee. This instance may be considered somewhat exceptional, though numerous parallel cases are known. Among ordinary flowers this intervention of the insect is largely a preferable intention, and though almost invariably fulfilled, a large proportion of flowers still retain, as a dernier ressort, the power of at least partial self-fertilization and perpetuity in the absence or neglect of their insect counterpart.
[Illustration: Fig. 14]
The numerous and conclusive demonstrations of Darwin, however, have proved that in the competition for existence such self-fertilized offspring quickly yield before the progeny of cross-fertilization.
But the distinctive feature of the orchids lies in the fact that this dependence on the insect is wellnigh universally absolute. Here are a great host of plants which are doomed to extinction if for any reason their insect sponsors should permanently neglect them. The principal botanical feature which differentiates the orchid from other plants lies in the construction of the floral organs, the pistil, stigma, and anthers here being united into a distinct part known as the column. The pollen is, moreover, peculiar, being collected into more or less compact masses, and variously concealed in the flower. Some of these are club-shaped, with a viscid extremity, others of the consistency of a sticking-plaster, and all are hidden from external view in pouches and pockets, from which they never emerge unless withdrawn on the body of an insect. The various devices by which this removal is insured are most astonishing and awe-inspiring. Nor is it necessary to go to the conservatory for a tropical specimen, as is commonly supposed. An orchid is an orchid wherever it grows, and our native list of some fifty species will afford examples of as strange mechanical adaptations as are to be found among Darwin's pages. Indeed, a few of our American species are there described. One example will suffice for present illustration-the sweet-pogonia or grass-pink of our sedgy swamps (Pogonia ophioglossoides). Its solitary rosy blossom, nodding on its slender stem above the sedges, is always a welcome episode to the sauntering botanist, and its perfume, suggesting ripe red raspberries, is unique in the wild bouquet. One of these flowers is shown in profile at Fig. 14, its various parts indexed. Concealed behind the petals is the column, elsewhere indicated from various points of view. Attracted by its color and fragrance, the insect seeks the flower; its outstretched fringy lip offers a cordial invitation at its threshold, and conducts its visitor directly to the sweets above. In his entrance, as seen at D (Fig. 15), the narrowed passage compresses his back against the underside of the column, forcing his head and back against the stigma. The effect of this inward pressure, as will be seen, only serves to force the anther more firmly within its pocket; but as the insect, having drained the nectar, now backs out, note the result. The lip of the anther catches upon the back, swings outward on its hinge, and deposits its sticky pollen all over the insect's back, returning to its original position after his departure. In another moment he is seen upon another blossom, as at D again, his pollen-laden back now coming in contact with the stigma, and the intention of the blossom is accomplished; for without this assistance from the insect the little lid remains close within its pocket, and the pollen is thus retained.
[Illustration: Fig. 15]
What startling disclosures are revealed to the inward eye within the hearts of all these strange orchidaceous flowers! Blossoms whose functions, through long eras of adaptation, have gradually shaped themselves to the forms of certain chosen insect sponsors; blossoms whose chalices are literally fashioned to bees or butterflies; blossoms whose slender, prolonged nectaries invite and reward the murmuring sphinx-moth alone, the floral throat closely embracing his head while it attaches its pollen masses to the bulging eyes, or perchance to the capillary tongue! And thus in endless modifications, evidences all of the same deep vital purpose.
Let us then content ourselves no longer with being mere "botanists"-historians of structural facts. The flowers are not mere comely or curious vegetable creations, with colors, odors, petals, stamens, and innumerable technical attributes. The wonted insight alike of scientist, philosopher, theologian, and dreamer is now repudiated in the new revelation. Beauty is not "its own excuse for being," nor was fragrance ever "wasted on the desert air." The seer has at last heard and interpreted the voice in the wilderness. The flower is no longer a simple passive victim in the busy bee's sweet pillage, but rather a conscious being, with hopes, aspirations, and companionships. The insect is its counterpart. Its fragrance is but a perfumed whisper of welcome, its color is as the wooing blush and rosy lip, its portals are decked for his coming, and its sweet hospitalities humored to his tarrying; and as it finally speeds its parting affinity rests content that its life's consummation has been fulfilled.