The Mother Decides the Sex 



mind. She therefore builds a partition per- 

 pendicular to the transversal partition which 

 she has just constructed and thus divides the 

 second storey into two rooms, a larger room, 

 in which she lodges a female, and a smaller, 

 in which she lodges a male. She next builds 

 a second transversal partition and a second 

 longitudinal partition perpendicular to it. 

 These once more give two unequal chambers, 

 stocked likewise, the large one with a female, 

 the smaller one with a male. 



From this third storey onwards, the Osmia 

 abandons goemetrical accuracy; the architect 

 seems to be a little out in her reckonings. 

 The transversal partitions become more and 

 more slanting and the work grows irregular, 

 but always with a sprinkling of large cham- 

 bers for the females and small chambers for 

 the males. Three females and two males are 

 housed in this way, the sexes alternating. 



By the time that the base of the eleventh 

 cell is reached, the transversal partition Is 

 once more almost perpendicular to the axis. 

 Here what happened at the bottom is re- 

 peated. 7'hcrc is no longitudinal partition; 

 and the spacious cell, covering the whole dia- 

 meter of the cylinder, receives a female. The 



IS3 



