226 SPECIAL INSTINCTS. _Chap. VIII. 



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 com- 

 menced at the same time, always standing at the proper relative 

 distance from the parts of the cells just begun, sweeping spheres ot 

 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 construction, 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 for- 

 mation of wax, it is known that bees are often hard pressed to get 

 sufficient nectar, and I am informed by Mr. Tegetmeier 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. More- 

 over, many bees have to remain idle for many days during the 

 process of secretion. A large store of honey is indispensable 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 import- 

 ant 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 inde- 

 pendent of the quantity of honey which the bees can collect. But 

 let us suppose that this latter circumstance determined, as it pro- 

 bably 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 through the winter, and 

 consequently required a store of honey : there can in this case be 

 no doubt that it would be an advantage to our imaginary humble- 

 bee, if a slight modification in her instincts led her to make her 

 waxen cells near together, so as to intersect a little ; for a wall in 

 common even to two adjoining cells would save some little labour 

 and wax. Hence it would continually be more and more advan- 



