Chap. VIIL] CELL-MAKING INSTINCT. 345 



If a number of equal spheres be described with their 

 centres placed in two parallel layers; with the centre 

 of each sphere at the distance of radius X \/ 2, or 

 radius X 1 "41421 (or at some lesser distance), from the 

 centres of the six surrounding spheres in the same 

 layer ; and at the same distance from the centres of the 

 adjoining spheres in the other and parallel layer ; then, 

 if planes of intersection between the several spheres in 

 both layers be formed, there will result a double layer 

 of hexagonal prisms united together by pyramidal bases 

 formed of three rhombs ; and the rhombs and the sides 

 of the hexagonal prisms will have every angle identi- 

 cally the same with the best measurements which have 

 been made of the cells of the hive-bee. . But I hear 

 from Prof. Wynian, who has made numerous careful 

 measurements, that the accuracy of the workmanship 

 of the bee has been greatly exaggerated; so much so, 

 that whatever the typical form of the cell may be, it is 

 rarely, if ever, realised. 



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 suppose the Melipona to 

 have the power of forming 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 by 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 accurately 



