The Distribution of the Sexes 



do was to lay some reed-stumps horizontally 

 within her reach, in the immediate neighbour- 

 hood of her usual haunts, namely, the nests 

 of the Mason-bee of the Sheds. Lastly, I 

 succeeded without difficulty in making her 

 build her nests in the privacy of my study, 

 with glass tubes for a house. The result sur- 

 passed my hopes. 



With both these Osmise, the division of 

 the gallery Is the same as with the Three- 

 horned Osmia. At the back are large cells 

 with plentiful provisions and widely-spaced 

 partitions; in front, small cells, with scanty 

 provisions and partitions close together. Also, 

 the larger cells supplied me w^Ith big cocoons 

 and females; the smaller cells gave me lit- 

 tle cocoons and males. The conclusion there- 

 fore Is exactly the same In the case of all 

 three Osmla^. 



Before dismissing the Osmiae, let us devote 

 a moment to their cocoons, a comparison of 

 which, in the matter of bulk, will furnish us 

 with fairly accurate evidence as to the relative 

 size of the two sexes, for the thing contained, 

 the perfect Insect, is evidently proportionate 

 to the silken wrapper In which It Is enclosed. 

 These cocoons are oval-shaped and may be 



109 



