Bramble-bees and Others 



of males and females according to the exi- 

 gencies of space in the actual nest which she 

 happens to be occupying. 



Just now, in the new nest, we saw the 

 Mason-bee arranging her total laying into 

 series first of females and next of males; and 

 here she is, mistress of an old nest of which 

 she has not the power to alter the arrange- 

 ment, breaking up her laying into sections 

 comprising both sexes just as required by the 

 conditions imposed upon her. She therefore 

 decides the sex of the egg at will, for, with- 

 out this prerogative, she could not, in the 

 chambers of a nest which she owes to chance, 

 deposit unerringly the sex for which those 

 chambers were originally built; and this hap- 

 pens however small the number of chambers 

 to be filled. 



When the nest is new, I think I see a reason 

 why the Mason-bee should seriate her laying 

 into females and then males. Her nest is a 

 half-sphere. That of the Mason-bee of the 

 Shrubs is very nearly a sphere. Of all shapes, 

 the spherical shape is the strongest. Now 

 these two nests require an exceptional power 

 of resistance. Without protection of any 

 kind, they have to brave the weather, one on 



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