874 THE ORIGIN OF SPECIES 



cell. It was most interesting to observe that, wherever 

 several bees had begun to excavate these basins near 

 together, they had begun their work at such a distance 

 from each other that by the time the basins had ac- 

 quired 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 intersection 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, rectangu- 

 lar 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; 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 experiment, 

 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 basins, as soon as they had been a littl© deepened, 

 came to have flat bases; and these flat bases, formed by 

 thin little plates of the vermilion wax 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 of wax. In 

 some parts, only small portions, in other parts, large 

 portions of a rhombic plate were thus left between the 



