dustrious of flower-guests, because they provide not only for their own needs, but also for those of their numerous progeny. Many of them are wise systematists, as Aristotle noted long ago, who wrote, "A bee on any one expedition does not pass from one kind of plant to another, but confines itself to a single species and does not change until it has first returned to the hive." Color must help them much; but since they visit a great variety of flowers, it is seemingly most useful as a means of distinguishing intermixed species, one color, in itself, being perhaps little more attractive than another.
Kerner, Kronfield, Forbes, and Della Torre have seen bumblebees fly for hours from one flower to another of the same kind, ignoring other species which grew mixed with them. To such persistent and intelligent industry our field and meadow flowers, at least in part, owe their endless variety of shape and color, and as long as bees live there will be fresh modifications for us to wonder at. The "soft sun-brush" directed by the exquisite taste of these little connoisseurs of true art is continually producing new chefs-d'œuvre.
Nor is the work of flies to be despised. Some of them are almost as enterprising and have apparently as keen a sense of beauty as many bees and butterflies. Müller speaks of the largest and most handsome of the saxifrages as the "masterpiece of the Syrphidæ" (the most highly developed of flies). Fly-flowers have often dark-red color and nectar so scanty that it does not pay the bees to take it—e. g., bryophyllum. In New Zealand flies largely take the place of bees, which are there exceedingly scarce. Some species are exclusively dependent on them. Lurid, snaking spots or markings or disgusting odors often tell the secret of fly-attraction (arum, Dutchman's pipe, skunk-cabbage, smilax).
But some flowers, neither showy nor fragrant, are yet abundantly visited both by bees and flies (bryonia, bur-cucumber, etc.). Kunth found that the greenish petals of some of these plants affect a photographic plate as strongly as those of white, violet, or blue flowers. It is not at all unthinkable that the wonderful eyes of insects may be sensitive to colors invisible to our coarser sense. Kunth adds that the glands of these plants may perhaps contain ethereal oils noticeable to insects though imperceptible to man.
Surely, in the face of all these facts, it can not be denied that there is some relation between the conspicuousness or fragrance of flowers and their pollinization and pollinizers, especially since it is possible in the various insect groups to trace a connection between the two, and since, in the absence of animals of one kind, others have sometimes been delegated to do the work, the botanical character of the region changing correspondingly; as, for