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Show 202 INSTINCT. [CHAP. VII rhon1bs; and the rhombs and the sides of the hexagonal prisms ·will have every angle identically the Rame with the best 1neasurements which have been made of the cells of the hive-bee. l-Ienee we may safely conclude that if we could slightly modify the instincts already possessed by the Melipona, and in thmnselves not very wonderful, this bee would make a structure as wonderfully perfect as that of the hive-bee. We must suppose the l\felipona to n1ake her cells truly spherical, and of equal sizes; and this would not be very surprising, seeing that she already does so to a certain extent, and seeing what perfectly cylindrical burrows in wood Inany insects can make, apparently by turning round on a fixed point. We n1ust suppose the Melipona to arrange her cells in level layers, as she already does her cylindrical cells; and we must further suppose, and this is the greatest difficulty, that she can son1ehow judge accurately at what distance to stand froin her fellow-labourers when several are Inaking their spheres; but she is already so far enabled to judge of distance, that she always describes her spheres so as to intersect largely; and then she unites the points of intersection by perfectly flat surfaces. We have further to suppose, but this is no difficulty, that after hexagonal prisms have been fol'lned by the intersection of adjoining spheres in the saine layer, she can prolong the hexagon to any length requisite to hold the stock of honey ; in the same way as the rude humble-bee adds cylinders of wax to the drcular mouths of her old cocoons. By such modifications of instincts in themselves not very wonderful,-hardly more wonderful than those which guide a bird to make its nest,-I believe that the hive-bee has acquired, through natural selection, her inimitable architectural powers. But this theory can be tested by experiment. Following the example of Mr. Tegetmeier, I separated two combs, and put between thmn a long, thick, square strip of wax : the bees instantly began to excavate minute circular pits in it ; and as they deepened these little pits, they made them wider and wider until they were converted into shallow basins, appearing to the eye perfectly true CnAP. VII.] CELLS OF THE HIVE-BEE. 203 or parts of a sphere, and of about the diameter of a cell. It was most interesting to me to observe th~t wherevm several bees had begun to excavate these basins near together they had begun their 'vork at such a distance from each other, that by t~e time the basi~s had acquire~ the above stated width (~. e. about the ~Idth of an o~dinary cell), and were in depth about one sixth of the diameter of the sphere of which they _formed a part, the rims of the basins intersected or broke Into each other. As soon as this occurred the bees ceased to excavate, and began to build up flat 'walls of wax on the lines of in~ersection ~etween the basins, so that each hexagonal prism was built upon the festooned edge of a ~mooth bas~n, ins.tead of on the straight edges of a three-sided pyramid as In the case of ordinary cells. . I then put into the hive, instea~ of a thic~c, square piece of wax, a thin and narrow, knife-edged ridge, coloured with vermillion. The bees instantly began on both sides to excavate little basins near to each other, in the san1e way as before; but the ridge of wax was so thin, that the bottoms of the basins, if they had been excavated to the same depth as in the former exp~rim~nt, would have broken into each other from the opposite Sides. The bees however, did not suffer this to happen, and they stopped their excavations in due time ; so that the basihs, as soon as they had been a little deepened, came to have flat bottoms; and these flat bottoms, formed by thin little plates of the vermillion wax having ~een left ungnawed, were situated, as far as the eye could Judge, exactly .along the planes of imaginary intersection between the basins on the opposite sides of the ridge o~ wax. In par~s, only little bits, in other parts, large portions ?fa rhombic plate had been left between the opposed basins, but the work, from the unnatural state .of things, had not been neatly performed. The bees mu~t h~ve worked .at very near~y the same rate on the opposite sides of the ndge of vermillion wax, as they circularly gnawed away and de~pened the basins on both sides in order to have succeeded 1n thus leaving flat plates bet~een the basins, by. stop pin~ work along the intermediate planes or planes of 1ntersect1on. |
