Chap. VIII.] CELL-MAKING INSTINCT. 345 



If a numter of equal spheres be described with 

 their centres placed in two parallel layers; with the cen- 

 tre of each sphere at the distance of radius X V ^j "'^ 

 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 hexagor.al 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. Wyman, who has made numerous careful 

 measurements, that the accuracy of the workmanship 

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

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

 rarely, if ever, realised. 



Eence we may safely conclude that, if we could 

 sKghtly modify the instincts already possessed by the 

 Mehpona, and in themselves not very wonderful, this 

 bee would make a structure as wonderfully perfect as 

 that of the hive-bee. We must suppose that Melipona 

 to have the power of forming her cells truly spherical, 

 and of equal sizes; and this would not be very surpris- 

 ing, seeing that she already does so to a certain extent, 

 and seeing what perfectly cylindrical burrows many in- 

 sects 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 cylindri- 

 cal cells; and we must further suppose, and this is the 

 greatest difficulty, that she can somehow judge accu- 



