246 SPECIAL INSTINCTS 



ing 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 many insects make in wood, apparently oy turning 

 round on a fixed point. We must 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 somehow judge accu- 

 rately at what distance to stand from her fellow-laborers 

 when several are making their spheres ; but she is already 

 so far enabled 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 flat sur- 

 faces. Bv such modifications of instincts which in them- 

 selves 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. 



But this theory can be tested by experiment. Following 

 the example of Mr. Tegetmeier, I separated two combs, and 

 put between them a long, thick, rectangular 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 or parts of a 

 sphere, and of about the diameter of a cell. It was most 

 interesting to observe that, wherever several bees had begun 

 to excavate tnese basins near together, they had begun their 

 work at such a distance from each other that by the time 

 the basins had acquired the above-stated width (i.e., about 

 the width of an ordinary 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 inter- 

 section between the basins, so that each hexagonal prism 

 was built upon the scalloped edge of a smooth basin, instead 

 of on the straight edges of a three-sided pyramid as in the 

 case of ordinary cells. 



I then put into the hive, instead of a thick, rectangular 

 piece of wax, a thin and narrow, knife-edged ridge, colored 

 with vermilion. The bees instantly began on both sides 

 to excavate little basins near to each other, in the same 

 way as before j but the ridge of wax was so thin, that the 



