280 ORIGIN OF SPECIES 



that a skilful workman with fitting tools and measures, 

 would find it very difficult to make cells of wax of the true 

 form, though this is effected by a crowd of bees working 

 in a dark hive. Granting whatever instincts you please, it 

 seems at first quite inconceivable how they can make all 

 the necessary angles and planes, or even perceive when they 

 are correctly made. But the difficulty is not nearly so great 

 as it at first appears: all this beautiful work can be shown, 

 I think, to follow from a few simple instincts. 



I was led to investigate this subject by Mr. Waterhouse, 

 who has shown that the form of the ceil stands in close 

 relation to the presence of adjoining cells; and the follow- 

 ing view may, perhaps, be considered only as a modification 

 of his theory. Let us look to the great principle of grada- 

 tion, and see whether Nature does not reveal to us her 

 method of work. At one end of a short series we have 

 humble-bees, which use their old cocoons to hold honey, 

 sometimes adding to them short tubes of wax, and likewise 

 making separate and very irregular rounded cells of wax. 

 At the other end of the series we have the cells of the hive- 

 bee, placed in a double layer: each cell, as is well known, 

 is an hexagonal prism, with the basal edges of its six sides 

 bevelled so as to join an inverted pyramid, of three rhombs. 

 These rhombs have certain angles, and the three which form 

 the pyramidal base of a single cell on one side of the comb 

 enter into the composition of the bases of three adjoining 

 cells on the opposite side. In the series between the extreme 

 perfection of the cells of the hive-bee and the simplicity of 

 those of the humble-bee we have the cells of the Mexican 

 Melipona domestica, carefully described and figured by Pierre 

 Hwber. The Melipona itself is intermediate in structure be- 

 tween the hive and humble-bee, but more nearly related to 

 the latter ; it forms a nearly regular waxen comb of cylin- 

 drical cells, in which the young are hatched, and, in addi- 

 tion, some large cells of wax for holding honey. These 

 latter cells are nearly spherical and of nearly equal sizes, and 

 are aggregated into an irregular mass. But the important 

 point to notice is, that these cells are always made at that 

 degree of nearness to each other that they would have inter- 

 sected or broken into each other if the spheres had been 



