CHAP. Tin.] CELL-JIAKTNG INSTINCT. 211 



build up a wall intermediate between two adjoining spheres ; but, 

 as far as I have seen, they never gnaw away and finish off the 

 angles of a cell till a large part both of that cell and of the adjoin- 

 ing cells has been built. This capacity in bees of laying down 

 under certain circumstances a rough wall in its proper place 

 between two just-commenced cells, is important, as it bears on a 

 fact, which seems at first subversive of the foregoing theory; 

 namely, that the cells on the extreme margin of wasp-combs are 

 sometimes strictly hexagonal ; but I have not space here to enter 

 on this subject. Nor does there seem to me any great difficulty in 

 a single insect (as in the case of a queen-wasp) making hexagonal 

 cells, if she were to work alternately on the inside and outside of 

 two or three cells commenced at the same time, always standing 

 at the proper relative distance from the parts of the cells just 

 begun, sweeping spheres or cylinders, and building up intermediate 

 planes. 



As natural selection acts only by the accumulation of slight 

 modifications of structure or instinct, each profitable to the indi- 

 vidual under its conditions of life, it may reasonably be asked, 

 how a long and graduated succession of modified architectural 

 instincts, all tending towards the present perfect plan of construc- 

 tion, could have profited the progenitors of the hive-bee ? I think 

 the answer is not difficult : cells constructed like those of the bee 

 or the wasp gain in strength, and save much in labour and space, 

 and in the materials of which they are constructed. With respect 

 to the formation of wax, it is known that bees are often hard 

 pressed to get sufficient nectar, and I am informed by Mr. Teget- 

 meier that it has been experimentally proved that from twelve to 

 fifteen pounds of dry sugar are consumed by a hive of bees for the 

 secretion of a pound of wax ; so that a prodigious quantity of fluid 

 nectar must be collected and consumed by the bees in a hive for 

 the secretion of the wax necessary for the construction of their 

 combs. Moreover, many bees have to remain idle for many clays 

 during the process of secretion. A large store of honey is indis- 

 pensable to support a large stock of bees during the winter ; and 

 the security of the hive is known mainly to depend on a large 

 number of bees being supported. Hence the saving of wax by 

 largely saving honey and the time consumed in collecting the 

 honey must be an important element of success to any family of 

 bees. Of course the success of the species may be dependent on 

 the number of its enemies, or parasites, or on quite distinct causes, 

 and so be altogether independent of the quantity of honey which 

 the bees can collect. But let us suppose that this latter circum- 

 stance determined, as it probably often has determined, whether a 

 bee allied to our humble-bees could exist in large numbers in any 

 country; and let us further suppose that the community lived 



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