Economy of Energy 



the recessed corners of the cell already built, 

 the Osmia runs up walls more or less curved, 

 upright or slanting, which intersect one an- 

 other at various points, so that each compart- 

 ment requires a new and complicated plan of 

 construction, which is very different from the 

 circular-partition style of architecture, with 

 its row of parallel dividing-disks. Moreover, 

 in this composite arrangement, the size of the 

 recesses left available by the earlier work to 

 some extent decides the assessment of the 

 sexes, for, according to the dimensions of 

 those recesses, the walls erected take in now 

 a larger space, the home of a female, and 

 now a smaller space, the home of a male. 

 Roomy quarters therefore have a double 

 drawback for the Osmia: they greatly increase 

 the outlay in materials; and they establish in 

 the lower layers, among the females, males 

 who, because of their earlier hatching, would 

 be much better placed near the mouth of the 

 nest. I am convinced of it: if the Osmia re- 

 fuses big reeds and accepts them only as a 

 last resort, when there are no others, it is 

 because she objects to additional labour and 

 to the mixture of the sexes. 



The Snail-shell, then, is but an indifferent 



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