| Comparison with 1859 | 
| 
 | 
| already does so to a certain extent, and seeing what perfectly cylindrical burrows in wood 
many insects can 
make, 
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 at what distance to stand from her fellow-labourers 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 largely; 
and then she unites the points of intersection by perfectly flat surfaces. ↑ We have further to suppose, but this is no difficulty, that after hexagonal prisms have been formed by the intersection of adjoining spheres in the same layer, she can prolong the hexagon to any length requisite to hold the stock of honey; in the same way as the rude humble-bee adds cylinders of wax to the circular mouths of her old cocoons.  By such modifications of instincts in themselves 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.| 1 blocks not present in  1859 1860 1861 1866 1869; present in  1872 |  | By such modifications of instincts which in themselves 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, 
 square 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 me to 
observe that 
wherever several bees had begun to excavate these basins near together, they had begun their work| square 1859 1860 |  | rectangular 1861 1866 1869 1872 | 
 | 
 
  
  
| already does so to a certain extent, and seeing what perfectly cylindrical burrows 
 in wood many insects 
 can| in wood 1859 1860 1861 1866 1869 |  | in wood1872 | 
make,| can 1859 1860 1861 1866 1869 |  | can1872 | 
apparently| make, 1859 1860 1861 1866 1869 |  | make 1872 | 
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 at what distance to stand from her fellow-labourers 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 
 largely;| apparently 1859 1860 1861 1866 1869 |  | in wood, apparently 1872 | 
and then she unites the points of intersection by perfectly flat surfaces. ↑| largely; 1859 1860 1861 1866 1869 |  | to a certain extent; 1872 | 
We have further to suppose, but this is no difficulty, that after hexagonal prisms have been formed by the intersection of adjoining spheres in the same layer, she can prolong the hexagon to any length requisite to hold the stock of honey; in the same way as the rude humble-bee adds cylinders of wax to the circular mouths of her old cocoons.  By such modifications of instincts in themselves 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.| 1 blocks not present in  1859 1860 1861 1866 1869; present in  1872 |  | By such modifications of instincts which in themselves 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 
 me to| rectangular 1861 1866 1869 1872 |  | square 1859 1860 | 
observe 
 that| me to 1859 1860 1861 1866 1869 |  | me to1872 | 
wherever several bees had begun to excavate these basins near together, they had begun their work| that 1859 1860 1861 |  | that, 1866 1869 1872 | 
 |