The Distribution of the Sexes 



the groups of cells, when finished, will have 

 the oldest in the central portion and the more 

 recent in the surrounding portion. Because 

 of this juxtaposition of the cells, which serve 

 partly as a wall to those which come next, 

 it is possible to form some estimate of the 

 chronological order of the cells in the Chalico- 

 doma's nests and thus to discover the sequence 

 of the two sexes. 



In winter, by which time the Bee has long 

 been in the perfect state, I collect Chalico- 

 doma-nests, removing them bodily from their 

 support with a few smart sideward taps of 

 the hammer on the pebbles. At the base of 

 the mortar dome, the cells are wide agape 

 and display their contents. I take the cocoon 

 from its box, open it and take note of the sex 

 of the insect enclosed. 



I should probably be accused of exaggera- 

 tion if I mentioned the total number of the 

 nests which I have gathered and the cells 

 which I have inspected by this method during 

 the last six or seven years. I will content 

 myself with saying that the harvest of a 

 single morning sometimes consisted of as 

 many as sixty nests of the Mason-bee. I had 

 to ha\e help in carrying home my spoils, even 



113 



