Bramble-bees and Others 



Mason-bee in the presence of an old nest. 

 She thereupon acts exactly as the Chalico- 

 doma does. She breaks up her laying, divides 

 it into series as short as the room at her dis- 

 posal requires; and each series begins with 

 females and ends with males. This break- 

 ing up, on the one hand, into sections in all 

 of which both sexes are represented and the 

 division, on the other hand, of the entire 

 laying into just two groups, one female, the 

 other male, when the length of the tube per- 

 mits, surely provide us with ample evidence 

 of the insect's power to regulate the sex of 

 the egg according to the exigencies of space. 

 And besides the exigencies of space one 

 might perhaps venture to add those connected 

 with the earlier development of the males. 

 These burst their cocoons a couple of weeks 

 or more before the females; they are the first 

 who hasten to the sweets of the almond-tree. 

 In order to release themselves and emerge 

 into the glad sunlight without disturbing the 

 string of cocoons wherein their sisters are still 

 sleeping, they must occupy the upper end of 

 the row; and this, no doubt. Is the reason 

 that makes the Osmia end each of her broken 

 layings with males. Being next to the door, 



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