174 
ANSMAL INTELLIGENCE. 
This statement having fully borne out bis theory, Mr. 
Darwin continues : — 
Hence we may safely conclude that, if we could slightly 
modify the instincts already possessed by the Melipona, and in 
themselves not very wonderful, this bee would make a structure 
as wonderfully perfect as that of the hive-bee. We must sup- 
pose the Melipona to have the power of forming her cells truly 
spherical, and of equal sizes; and this would not be very sur- 
prising, seeing that she already does so to a certain extent, and 
seeing what perfectly cylindrical burrows many insects make in 
wood, apparently by turning round on a fixed point. We must 
suppose the Melipona to arrange her cells in level layers, as sue 
already does her cylindrical cells ; and we must further suppose 
— and this is the greatest difficulty — that she can somehow judge 
accurately at what distance to stand from her fellow-labourers 
when several are making their spheres ; but she is already so 
far able to judge of distance that she always describes her 
spheres so as to intersect to a certain extent ; and then she 
unites the points of intersection by perfectly fiat surfaces. By 
such modifications of instinct, which in themselves are 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 . 1 
Mr. Darwin next tested this theory by the experiment 
of introducing into beehives plates of w~ax, and observing 
that the bees worked upon these plates just as the theory 
required. That is to say, they made their cells by ex- 
cavating a number of little circular pits at equal distances 
from one another, so that by the time the pits had ac- 
quired the width of an ordinary cell, the sides of the pits 
intersected. As soon as this occurred the bees ceased to 
excavate, and instead began to build up flat walls of wax 
on the lines of intersection. Other experiments with very 
thin plates of vermilion-coloured wax showed that the 
bees all worked at about the same rate, and on opposite 
sides of the plates, so that the common bottoms of any 
two opposite pits were flat. These flat bottoms 6 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 of wax ; ’ so that if the 
L Origin of Species , ( Cell-making Instinct.’ 
