The courtship of another species, Dendryphantes capitatus, in which the sexes are entirely different, is described as follows:
“The males of capitatus are very quarrelsome, sparring whenever they meet, chasing each other about, and sometimes clinching. It is a very abundant spider with us, so that we often put eight or ten males into a box to see them fight. It seemed cruel sport at first, but it was soon apparent that they were very prudent little fellows, and were fully conscious that ‘he who fights and runs away will live to fight another day.’ In fact, after two weeks of hard fighting we were unable to discover one wounded warrior. When the males are approaching each other, they hold the first legs up in a vertical direction. Sometimes they drop the body on to one side as they jump about each other. These movement are very quick, and they are always ready for a passage at arms. When courting the females they have another movement. They approach her rapidly until within two to five inches, when they stop and extend the first legs directly forward, close to the ground, the legs being slightly curved with the tips turned up. (Fig. 18). Whether it be intentional or not, this position serves admirably to expose the whole of the bronze and white face to the attentive female, who watches him closely from a little distance. (Fig. 19.) The males also give their palpi a circular movement, much as a person does when washing his hands. As he grows more excited, he lies down on one side with his legs still extended. These antics are repeated for a very long time, often for hours, when at last the female, either won by his beauty or worn out by his persistence, accepts his addresses.” (Pp. 45, 46.)
In another species, Dendryphantes elegans, both sexes are brilliantly colored.
“The male is covered with iridescent scales, his general color being green; in the female the coloring is dark, but iridescent, and in certain lights has lovely rosy tints. In the sunlight both shine with the metallic splendor of hummingbirds. The male alone has a superciliary fringe of hairs on either side of his head, his first legs being also longer and more adorned than those of his mate. The female is much larger, and her loveliness is accompanied by an extreme irritability of temper which the male seems to regard as a constant menace to his safety, but his eagerness being great, and his manners devoted and tender, he gradually overcomes her opposition. Her change of mood is only brought about after much patient courting on his part. While from three to five inches distant from her he begins to wave his plumy first legs in a way that reminds one of a wind-mill. She eyes him fiercely and he keeps at a proper distance for a long time. If he comes close she dashes at him and he quickly retreats. Sometimes he becomes bolder and when within an inch, pauses, with the first legs outstretched before him, not raised as is common in other species; the palpi also are held stiffly out in front with the points together. Again she drives him off, and so the play continues. Now the male grows excited as he approaches her, and while still several inches away whirls completely around and around; pausing, he runs closer and begins to make his abdomen quiver as he stands on tip-toe in front of her. Prancing from side to side, he grows bolder and bolder, while she seems less fierce, and yielding to the excitement lifts up her magnificently iridescent abdomen, holding it at one time vertically and at another sideways to him. She no longer rushes at him, but retreats a little as he approaches. At last he comes close to her, lying flat, with his first legs stretched out and quivering. With the tips of his front legs he gently pats her; this seems to arouse the old demon of resistance, and she drives him back. Again and again he pats her with a caressing movement, gradually creeping nearer and nearer, which she now permits without resistance until he crawls over her head to her abdomen, far enough to reach the epigynum with his palpus”. (Pp. 46-47.)
If we lay no emphasis on the implied emotional elements in the behavior of the spiders in this description—terms of emotion borrowed direct from human psychology—there still remain the several types of apparently significant reactions associated with courtship. The statements leave no room for doubt that vision plays an important rôle in the complex reflexes that lead gradually to successful mating. The Peckhams insist that the display of the male is always of a kind to bring before the female the special adornments of the male in whatever part of the body they may lie. The chance of subjective interpretation here is so great that unless the results are carefully checked up by studies of the attitudes assumed by males in species in which the males are without ornament, their interpretation must be taken with the greatest reserve. Assigning, as our authors do, so much by gratuitous implication to the emotional side of the picture prejudices one, perhaps too greatly, against accepting a special (even an implied intentional) exhibition of the specially ornamented parts. On the other hand, if it be conceded that the conspicuousness of the male is an element in the reaction, the very special adornments visible from the front might be supposed to enhance the effect produced in the female. Similar displays of special ornamentation in the male have been described both for birds and insects, but here, too, the question has been raised as to whether such exhibitions are more than an accidental accompaniment of the posturing of the male, for the same kind of behavior is known to occur in other cases where the male is unornamented and resembles the female. Had such a male special ornamentation it would no doubt appear to us that his behavior was “calculated” to display his ornaments.
Dr. and Mrs. Peckham point out that their observations are entirely inconsistent with Wallace’s interpretation of the origin of secondary sexual characters. They find no evidence in favor of his view that the male possesses greater “vital activity.” On the contrary, the female is the more active and pugnacious of the two. They also object to Wallace’s statement of a total absence of any evidence that the female notices the display of the male. In spiders the females “observe” the males with close attention during their courtship. They point out also that, in spiders at least, as the female gradually becomes adult, a male if preferred will have a chance of mating with several females, “and as the mating season lasts for two or three weeks the more brilliant males may easily be selected again and again.” In regard to Wallace’s argument as to the distribution of accessory plumes in humming birds, the Peckhams point out that—
“The pectoral muscles reach their highest development in the hummingbirds, the diurnal birds of prey, and the swallows, and we may, therefore, fairly use these groups to test Mr. Wallace’s explanation of breast plumes. In the swallows and birds of prey we find no such appendages, in spite of their further claim to them, on the ground of great vigor and activity. As to the humming-birds, we find in the genus Aglæactis six species with more or less developed breast-plumes, which are also found in nine other species, scattered through different genera—in all, only fifteen species out of four hundred and twenty-six; while we find in fifty-six species the lengthened and modified tail-feathers, which, according to Mr. Wallace’s view, should be peculiar to the Gallinaceæ.
“Again, there are elongated feathers from the throat or from the side of the neck in thirty-five species, while seventeen have crests from the top of the head, and seventeen, downy puffs from the tarsi.”[11]
From this brief survey of the family we see that, contrary to what we should expect from Mr. Wallace’s theory, although the breast muscles are the seat of the highest activity, breast plumes are the least frequent of all the forms of ornamental plumage.
“We may fairly say, then, that the humming-birds completely refute the proposition that there is any relation between the development of color and accessory plumes and ‘surfaces where muscular and nervous development is considerable.’”[12]