I have just adverted to the ingenuity of the bees in thickening, and thereby strengthening the mouths of the cells. _Additional strength is also derived from the bees covering the whole surface of the combs, but more particularly the edges of the cells, with a peculiar kind of varnish_, which they collect for the purpose. At first the combs are delicately white, semitransparent, and exceedingly fragile, smooth but unpolished: in a short time their surfaces become stronger, and assume more or less of a yellow tint. The deepening of the colour of honey-combs has been supposed, by some, to be the effect of age; and in part it may be: but it is principally owing to the coat of varnish with which the bees cover them. This varnish strongly resembles propolis, appearing to differ from it only in containing the colouring material which imparts to wax its yellow hue. The source of this colouring matter has not been discovered: it is insoluble in alcohol; but the manufacture of white wax shows that it is destructible by light.--But to return to the construction of the cell-work. _The pyramidal basis of a cell is formed by the junction of three rhomboidal or lozenge-shaped portions of wax;_ thus, [Illustration] the apex of the pyramid being situated where the three obtuse angles of the lozenges meet. To the exterior edges and angles are attached the six pannels or sides of each cell. The apex of each pyramidal bottom, on one side of a comb, forms the angles of the bases of three cells on the opposite side, the three lozenges respectively concurring in the formation of the bases of the same cells. This will I hope explain what is meant by "each cell separately weak, being strengthened by coincidence with others." The bottom of each cell rests upon three partitions of opposite cells, from which it receives a great accession of strength. As it is desirable that the reader should thoroughly comprehend this subject, I will restate it in other words.--The partition which separates the two opposing rows of cells, and which occupies, of course, the middle distance between their two surfaces, is not a plane but a collection of rhombs, there being three at the bottom of each cell: the three together form in shape a flattened pyramid, the basis of which is turned towards the mouth of the cell; each cell is in form therefore an hexagonal prism, terminated by a flattened trihedral pyramid, the three sides of which pyramid are rhombs, that meet at the apex by their obtuse angles. The plates underneath, represent the opposite surfaces of the pyramidal bases of adjoining cells, and will, I trust, enable the reader to understand the foregoing description. [Illustration] The union of the lozenges in one point, in addition to the support which it is the means of affording to the three partitions between opposing cells, is also admirably adapted to receive the little egg and to concentrate the heat necessary for its incubation.