« AnteriorContinuar »
two of the opposite angles of the hexagon,
Fig. 3. Fig. 3, A, a, will be in the same vertical line, and two of the sides will be parallel to this. The same is true of the opposite side of the comb; and thus all the corresponding parts of the cells on the two sides will be par- BA allel. In the deviation we are now noticing, the change is like that represented in A, where the cell a is in its true position, while the cell b, which is from the opposite side, and is in contact with a, varies from it by about 30°. If we look at these two cells in the direction of their sides as at B, the prism a will have one of its angles towards the eye, and 6 one of its sides. If rows of cells are constructed on each of the sides a and b, Fig. 3, B, it will be seen that the rows thus formed on the two faces of the comb will cross each other continually. A modification of this variety is seen at C, where the axes of the two adjoining prisms, instead of being separated as usual by the semidiameter of a cell, coincide ; consequently, as the apices of the angles of a project beyond the sides of b, a will not only be in contact with b, but by its angles with the six cells by which b is surrounded. In either of these cases the pyramidal base becomes impracticable, and the flat bottom of the cell is substituted for it almost as a matter of necessity. The bottoms of the cells being flat, it is obvious that the change of position by rotation of the cell on its axis may be carried to any extent, without leading to an interference with the cells of the opposite side ; in fact several degrees of it have been observed.
Since the mouths of such cells are in the same plane with those normally constructed in the same comb, and since the pyramidal base is cut off, they are shortened by an amount equal to the height of that of the base, and therefore are of a proportionately less capacity than the normal cell. Nevertheless, such truncated cells are used for rearing. the young, and, like the others, were found to contain cocoons.
In curved or bent combs the cells on the concave side tend to become narrower, while those on the other tend to become broader towards their mouths. The bees meet this emergency in one of the following ways:
On the convex side,
1st. By allowing the cavity of this cell to become broader, without any correction being made.
2d. By thickening the walls of the cell in proportion to its tendency to become broader, and thus keeping the diameter of its cavity uniform.
3d. When the divergence reaches a certain amount, by making a false-cell, with a pointed bottom, between the diverging cells.
On the concave side, —
2d. When two adjoining cells converge so much as to render the mouth too small, the walls between them are suppressed at a certain point, and thus the two mouths are merged, and the compound cell thus formed has a double base, and but one entrance, the two cells being combined, as are certain kinds of twin crystals, or of double monsters. The form of the mouth under these circumstances is, however, liable to a considerable range of variation, as in the central line
of cells in Fig. 4,* in which are a Fig. 4.
variety of hexagons. That on the line a, b has three sides at one
end, united by two long sides with MO one at the other, and thus two of
the opposite sides are not parallel ; at c, d, two sides at either end are united by two long sides, these last being parallel; and at e, f, the mouth of the compound cell has seven sides. Each has a partition at its base, separating the two originally distinct cells, and each was lined with a cocoon, showing that it had been used for rearing young.
In combining the mouths of two adjoining cells, it will be seen that this does not consist merely in
suppressing the partition between them; for if this were so, each of the long sides would contain more or less of an angle, as at the lower side of g, according to the degree of convergence, until three of the sides of each of the combining cells had disappeared. Instead of this, the portions of two sides forming the angle just referred to are replaced by one straight side, as on the upper side of g, and in both of the long sides of the undulating line of cells above it.
* Figs. 4, 5, and 6 are made from impressions obtained directly from the comb and transferred to wood. They represent the forms of the cells exactly.
Drone Cells. — These are liable to substantially the same variations as the worker cells. Reaumer observed that they were larger by one ninth in one diameter than in another.* Four pieces of drone comb gave the following measurements.
I., II., III., in the above table, indicate the diameters drawn perpendicularly to the three pairs of sides of the hexagons, and series 1, 2, 3 indicate measurements of cells made from three portions of each comb. Ten cells were measured in each case.
In comparing all of the above measurements, it is found that the smallest aggregate diameter of any ten cells is 2.36 inches, and the largest, 2.80 inches, making an extreme difference of 0.44 inch, or the diameter of a drone and almost that of a worker cell in addition. The greatest variation in any one series was 0.21, or a little more than four fifths of the diameter of a drone cell, which is somewhat less than the quantity given by Reaumer.
The following measurements from twelve consecutive rows of cells, of ten each, from the middle of a piece of drone comb, show the progressive variation from one row to another. 1st row 2.47 inches.
7th row 2.64 inches. 2d« 2.50
2.67 3d “ 2.51 €
2.67 “ 4th "
11th " 2.63 "
12th “ 2.65 · 6
Transition Cells. — As drone are one fifth larger than worker cells, and as both are combined in one and the same piece of comb, a transition cannot be made from one to the other without some disturbance in the regularity of the structure. It would be a nice problem to determine the way in which this could be effected with the greatest economy of space and material. The bees do not appear to have any systematic method of making such a change. More commonly, they effect it by a gradual alteration of the diameters, thus enlarging a worker into a drone, or narrowing a drone into a worker cell. This alteration is usually made in from four to six rows. The following table gives an illustration of the rate of alteration in such a case, beginning with four drone cells of the usual size, and ending with four worker cells.
Four drone cells measured in the
This last measurement exactly equals that of four worker cells. The rate of the reduction of the size of the cell is not uniform, the differences between successive rows being .05,.02, .01, .03, .03 inch. We have, however, seen the transition made with two rows of transitional Fig. 5.
cells, and as in Fig. 5, with only one. In this last case, the regularity of two adjoining rows is sacrificed.
In consequence of the gradual narrowing or widening of the transition cells, the comb tends to become more or less triangu
lar and the cells to become disturbed. The bees counteract this tendency by the occasional intercalation of an additional row, of which two instances are given in Fig. 6, at a and b, where three rows of worker cells are continuous with two of drone cells, c d and e f; or, reversing the statement, and supposing the transition, as in the building of the comb, is from worker to drone cells, a row of the latter is from time to time omitted as the rows a and b; in this way,
the regularity of the comb is preserved.* This, however, is not done at definite intervals ; for in one piece of comb two intercalated series were nine cells apart, in another, six, and in another, four.
Mr. Langstroth has given a good figure, illustrating the form of the mouths of some of the cells where the worker and drone cells come together.f
The presence of a fourth face in the base of the transitional cells is by no means constant, as asserted by several observers, for we have seen the change from worker to drone cells without the fourth face appearing in any of them.
In all the transitional cells of brood-comb cocoons are invariably found, showing that they have been occupied. It is obvious that some of these would be either too large for a worker or too small for a
* This figure was made from a piece of old brood-comb, in which the lip of the drone cells was very much thickened, and the mouths were almost circular. There is nothing abnormal in this, except at those points where the row of intercalated cells, as a and b, connect with the drone cells.
+ Treatise on the Bee, p. 74 and Pl. XV.