INSTINCT 379 



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 adjoining 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 sub- 

 versive 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) mak- 

 ing 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, sweep- 

 ing spheres or cylinders, and building up intermediate 

 planes. 



As natural selection acts only by the accumulation of 

 slight modifications of structure or instinct, each profit- 

 able to the individual under its conditions of life, it may 

 reasonably be asked, how a long and graduated succes- 

 sion of modified architectural instincts, all tending toward 

 the present perfect plan of construction, could have prof- 

 ited 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 labor and 

 space, and in the materials of which they are constructed. 

 I 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. Tegetmeier that it has been experi- 

 mentally proved that from twelve to fifteen pounds of 



