THE HIVE BEE. 433 



In the first place, the Bee must strike perfect circles from 

 centres the distance of which from each other must he accurately 

 adjusted. Again, these centres must be so placed that the centre 

 of the circle sculptured on one side of the comb must be equi- 

 distant from the centres of the three adjacent circles on the 

 other side — a problem of no easy accomplishment, even with 

 the aid of rule and compass. Then, if the circles be not perfect, 

 or their centres wrongly placed, or the hollow of one cut deeper 

 than that of another, or the hemispherical form of the hoUow 

 not precisely just, the whole accuracy of the angles is destroyed, 

 and the entire comb would be as distorted as the first essays of a 

 young carpenter. 



Then there is another explanation, which may be called the 

 " equal pressure " theory. The Bee is, according to the advocates 

 of this theory, supposed to construct all the cells of a cylindrical 

 shape, and the cells are supposed to assume the hexagonal 

 form by equal pressure in all directions. Every one knows that 

 cylinders made of a yielding substance, always become hexagonal 

 if pressed together, and a similar process was supposed to cause 

 the hexagonal shape of the bee-cell. 



There is another theory, which I believe to be entirely original, 

 which is suggested by the well-known mathematician and 

 crystallographer above mentioned. Mr. Mitchell wiites to me as 

 follows : " It may not be out of place to remark that the bee- 

 cell forms a mould, as it were, of the natural form of a crystal. 

 There is in nature a great variety of crystals, hexagonal prisms 

 terminated by three planes, like the bee-cell. These have many 

 different angles. But there is one form, called the rhombic 

 dodecahedron, see fig. 6, very frequently found in natural 

 crystals of the garnet, which has precisely the same angles as 

 the bee-ceU. 



" Certain crystals split naturally into planes precisely like the 

 lozenges which have already been described in giving the key to 

 the structure of the bee-cell. May it not, therefore, be possible 

 that wax, which is a crystaUizable substance, cleaves in this 

 particular direction, and does the Bee use this property in form- 

 ing its cell ? Though this vague conjecture should prove to be 

 true, we shall not less admire the marvellous instinct which 

 combines this fact with the structure of the cell." 



It would, of course, be easy to fill many pages with the 



FF 



