The Distribution of the Sexes 



and an egg, the second in order of primogeni- 

 ture. And so it goes on, storey by storey, un- 

 til the cylinder is full. Then a thick, plug of 

 the same green material of which the parti- 

 tions are formed closes the home and keeps 

 out marauders. 



In this common cradle, the chronological 

 order of births is perfectly clear. The first- 

 born of the family is at the bottom of the 

 series; the last-born is at the top, near the 

 closed door. The others follow from bot- 

 tom to top in the same order in which they 

 followed in point of time. The laying is num- 

 bered automatically: each cocoon tells us its 

 respective age by the place which it occupies. 



To know the sexes, we must wait for the 

 month of June. But it would be unwise to 

 postpone our investigations until that period. 

 Osmia-nests are not so common that we can 

 hope to pick one up each time that we go out 

 with that object; besides, if we wait for the 

 hatching-period before examining the bram- 

 bles, it may happen that the order has been 

 disturbed through some insects having tried 

 to make their escape as soon as possible after 

 bursting their cocoons; it may happen that 

 the male Osmia?, who are more forward than 



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