The Mason-bees 



chanced to find herself the mistress of an- 

 other's nest. She took advantage of this to 

 entrust her egg to it. This expeditious 

 method, so easy for the mother and so fa- 

 vourable to the success of her offspring, made 

 such an impression on her that she transmitted 

 the maternal indolence to her posterity. 

 Thus the worker gradually became trans- 

 formed into a parasite. 



Capital ! The thing goes like clockwork, 

 as long as we have only to put our ideas on 

 paper. But let us just consult the facts, if you 

 don't mind; before arguing about probabili- 

 ties, let us look Into things as they are. Here 

 is the Mason-bee of the Sheds teaching us 

 something very curious. To smash the lid of 

 a cell that does not belong to her, to throw 

 the egg out of doors and put her own In its 

 place is a practice which she has followed 

 since time began. There Is no need of my 

 Interference to make her commit burglary: 

 she commits it of her own accord, when her 

 rights are prejudiced as the result of a too- 

 long absence. Ever since her race has been 

 kneading cement, she has known the law of 

 retaliation. Countless ages, such as the evo- 

 lutionists require, have made her adopt forcl- 

 236 



