to be seen minute globular bodies, to be finally set free by the rupture of the capsule, as free swimming Jellyfishes. (See Plate 8, fig. 12: a, fixed individual; b, capsule containing young Jelly-fishes.) Others bud directly from the twig and drop off singly, as in Coryne. (Fig. 7, buds forming from Hydroid stalk; Fig. 6, adult Coryne.) These are found by thousands in spring time. Not only do these free Jelly-fishes bud from fixed communities, but in one species young ones bud from the Jelly-fish itself, as in Lizzia (Fig. 10), and certain others where the young bud from the stomach. All these Hydroid Jelly-fishes produce eggs, which again give rise to plant-like communities. At another time we hope to devote a chapter to the structure of Jelly-fishes, and illustrate more fully the character of the Hydroids, of which we have scarcely touched in this paper.

EXPLANATION OF PLATE 8.

Fig. 1. Early condition of Aurelia,—after AGASSIZ.

Fig. 2. Older condition of same, showing individuals about to separate, after AGASSIZ.

Fig. 3. Aurelia, a short time after freeing itself, - original.

Fig. 4. Advanced stage of above,―original.

Fig. 5. Aurelia, in adult condition, — after AGASSIZ.

Fig. 6. Coryne mirabilis Ag., -original.

Fig. 7. Hydroid community of Coryne magnified, showing Jellyfish buds about to separate,

after CLARK.

Fig. 8. Pleurobrachia, —after A. AGASSIZ.

Fig. 9. Tima formosa Ag.,-original.

Fig. 10. Lizzia grata Ag., showing young ones budding from

stomach, original.

Fig. 11. Hydroid community of Eucope diaphana Ag.,—after A.

AGASSIZ.

Fig. 12. Showing one twig of Eucope with fixed individual A, and reproductive capsule B, containing a number of young Jelly-fishes, after A. AGASSIZ.

Fig. 13. Eucope, in adult condition, magnified, — original.

254

AGENCY OF INSECTS IN FERTILIZING PLANTS.

BY W. J. BEAL.

MR. CHARLES DARWIN and other botanists have proved beyond a doubt, that some flowers, in which the pollen may easily gain access to the stigma of the same flower, are sterile unless fertilized by pollen borne from other flowers, while many are much more productive by a cross fertilization.

For information concerning the peculiar manner in which fertilization is effected in the Balsam, Wood-sorrel, Violets, Dicentra or Dielytra, Corydalis, Mitchella or Partridge-berry, Oldenlandia or Houstonia, Primrose, Barberry, Lysimachia or Loosestrife, Orchids, Dutchman's Pipe, and others; consult the observations recorded by Mr. J. T. Rothrock in the second number of the NATURALIST, Mr. Darwin's work on the "Fertilization of Orchids," and seven articles by Dr. A. Gray in the "American Agriculturist," beginning in May, 1866.

With the fact that insects are necessary to fertilize some plants, and the theory that all are improved by crossing, let us see how this is accomplished in plants which may not seem to require the aid of the wind or insects. Plants are very rarely found in which the pollen may not, occasionally at least, get to the stigma of another flower of the same, or an allied species. Then if the pollen is “prepotent" or most effective on stigmas when thus transferred, a cross is very sure to result, even though much pollen. comes in contact with the stigma of the same flower. Dr. Gray, acquainted with these facts, and familiar with the structure of the Iris, saw that insects must be needed for the fertilization of this plant also, and without seeing the bees upon them, shrewdly pointed out the manner in which

they must carry the pollen from one flower to another. We verified his theory by observations made two years ago, and found it to be true in the essential particulars.

Without giving a scientific description of the flower, it is enough for our present purpose to say, that the parts consist of three curved tubes, each just about large enough to admit a common honey-bee, being a trifle larger than a cell in her comb.

There is a showy crest, or attractive platform, projecting at the outer end of each tube upon which the bee first alights. When going into the flower for the first time during the day, she is free from pollen. She brushes against a lid which hangs from above, not unlike an oldfashioned swinging door of a cat-hole, as sometimes seen about barns or corn-cribs. When farther in beyond the lid, she comes against the anther, which only discharges pollen on the side next to the bee's back. After getting what nectar she can at the lower end of the tube, shebacks out again, pushing the trap-door in the opposite direction. The outside of this door is the only part of the stigma upon which the pollen will produce any effect, so upon visiting the first tube no pollen adheres to the sensitive side of the stigma, although the bee leaves the place with her back well powdered. Calling at another tube, she dives in as before, this time dusting the outside of the lid with pollen which was brought from the tube first visited.

In the early part of June, I examined the common Blue Flag (Iris versicolor Linn.) at different times during the day, and always succeeded in seeing the bees at work while their heads and backs contained an abundance of pollen. In wilted flowers, and in some that were fresh, I saw bees occasionally get in and out at the side of the

tube, without touching the stigma at all. Sometimes they went in the tube as first described, and then slipped out at the side instead of backing out. Several went on top of the flower and tried to find other ways to get at the sweets below, but in every instance they failed, and soon left that position.

At the Botanical Garden, Cambridge, Mass., I noticed bees on several foreign species of Iris, in some of which, as Iris pseudocarus of Southern Europe, the tube is more nearly perfect, so that it is impossible for them to find a side entrance or egress.

The corolla of Andromeda floribunda Pursh, is nearly urn-shaped, hanging with the open end or entrance down. The ten long anthers open at the apex by two round holes, and each anther is supplied with two horizontal or reflexed awns on the outside next the corolla. The stigma is just at the narrow mouth of the corolla. Bees in abundance visit the flowers, thrusting their long tongue or proboscis against the awns or horns of the anther, as they reach in for nectar which is secreted farther on. By hitting the awns the anthers are disturbed, and the holes brought close against some part of the bee's proboscis, which is well sprinkled over with pollen, as well as the other mouth parts hanging below the flower. Bees were examined, and found to have the parts mentioned covered with the four-grained pollen which is peculiar to a few plants.

I cannot see how pollen alights on the stigmas of this plant, for in falling out in the natural way it must pass by to the ground. But the insect puts the material in place every time as effectually as a mason can stick mortar on the ceiling of a room. The Blueberry (Vaccinium) is similar in structure to the Andromeda, except that the