246 THE WONDERS OF INSTINCT 



varied was the number of cells in the long tubes and the 

 proportion between the two sorts of cocoons, sometimes 

 males predominating and sometimes females. 



When confronted with tubes too small to receive all 

 her family, the Osmia is in the same plight as the Mason- 

 bee in the presence of an old nest. She thereupon acts 

 exactly as the Chalicodoma does. She breaks up her 

 laying, divides it into series as short as the room at her 

 disposal demands; and each series begins with females 

 and ends with males. This breaking up, on the one 

 hand, into sections in all of which both sexes are repre- 

 sented 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 permits, surely provides 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 develop- 

 ment 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, these impatient ones will leave 

 the home without upsetting the shells that are slower in 

 hatching. 



I had offered at the same time to the Osmiae in my 



