The Mother Decides the Sex 



lowed by a third and so on, one after the 

 other, as long as any remain unoccupied and 

 the mother's ovaries are not exhausted. 

 Finally, the dome receives, mainly over the 

 apertures already plugged, a coat of plaster 

 which makes the nest look like new. If she 

 has not finished her laying, the mother goes 

 in search of other old nests to complete It. 

 Perhaps she does not decide to found a new 

 establishment except when she can find no 

 second-hand dwellings, which mean a great 

 economy of time and labour. In short, 

 among the countless number of nests which 

 I have collected, I find many more ancient 

 than recent ones. 



How shall we distinguish one from the 

 other? The outward aspect tells us nothing, 

 owing to the great care taken by the Mason 

 to restore the surface of the old dwelling 

 equal to new. To resist the rigours of the 

 winter, this surface must be Impregnable. 

 The mother knows that and therefore repairs 

 the dome. Inside, It Is another matter: the 

 old nest stands revealed at once. There are 

 cells whose provisions, at least a year old, are 

 intact, but dried up or musty, because the egg 

 has never developed. There arc others con- 



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