Chap. VIII.] CELL-MAKING INSTINCT. 227 



tageous to our humble-bees, if tbey were to make their cells more 

 and more regular, nearer together, and aggregated into a mass, like 

 the cells of the Melipona ; for in this case a large part of the 

 bounding surface of each cell would serve to bound the adjoining 

 cells, and much labour and wax would be saved. Again, from the 

 same cause, it would be advantageous to the Melipona, if she were 

 to make her cells closer togetber, and more regular in every way 

 than at present ; for then, as we have seen, the spherical surfaces 

 would Avholly disappear and be replaced by plane surfaces ; and the 

 Melipona would make a comb as perfect as that of the hive-bee. 

 Beyond this stage of perfection in architecture, natural selection 

 oould not lead ; for the comb of the hive-bee, as far as we can see, 

 is absolutely perfect in economising labour and wax. 



Thus, as I believe, the most wonderful of all known instincts, 

 that of the hive-bee, can be explained by natural selection having 

 taken advantage of numerous, successive, slight modifications of 

 simpler instincts ; natural selection having, by slow degrees, more 

 and more perfectly led the bees to sweep equal spheres at a given 

 distance from each other in a double layer, and to build up and 

 excavate the wax along the planes of intersection; the bees, of 

 course, no more knowing that they swept their spheres at one par- 

 ticular distance from each other, than they know what are the 

 several angles of the hexagonal prisms and of the basal rhombic 

 plates ; the motive power of the process of natural selection having 

 been the construction of cells of due strength and of the proper 

 size and shape for the larvaa, this being effected with the greatest 

 possible economy of labour and wax ; that individual swarm which 

 thus made the best cells with least labour, and least waste of honey 

 in the secretion of wax, having succeeded best, and having trans- 

 mitted their newly-acquired economical instincts to new swarms, 

 which in their turn will have had the best chance of succeeding in 

 the struggle for existence. 



Objections to the TJieory of Natural Selection as applied to Instincts : 

 Neuter and Sterile Insects. 

 It has been objected to the foregoing view of the origin of instincts 

 that " the variations of structure and of instinct must have been 

 simultaneous and accurately adjusted to each other, as a modifica- 

 tion in the one without an immediate corresponding change in th.8 

 other would have been fatal." The force of this objection rests 

 entirely on the assumption that the changes in the instincts and 

 structure are abrupt. To take as an illustration the case of the 

 krger titmouse (Parus major) alluded to in a previous chapter; 



Q 2 



