The Theory of Parasitism 



walls of a porch facing the south. Here, on a 

 level with my head, placed so that they can 

 easily be observed, hang some tiles removed 

 from the neighbouring roofs in winter, to- 

 gether with their enormous nests and their 

 occupants. Every May, for five or six years in 

 succession, I have assiduously watched the 

 works of my Mason-bees. From the mass of 

 my notes on the subject I take the following 

 experiments which bear upon the matter un- 

 der discussion. 



Long ago, when I used to scatter a handful 

 of Chalicodomae some way from home, in 

 order to study their capacity for finding their 

 nest again, I noticed that, if they were too 

 long absent, the laggards found their cells 

 closed on their return. Neighbours had 

 taken the opportunity to lay their eggs there, 

 after finishing the building and stocking It 

 with provisions. The abandoned property 

 benefited another. On realizing the usurpa- 

 tion, the Bee returning from her long journey 

 soon consoled herself for the mishap. She 

 began to break the seals of some cell or other, 

 adjoining her own; the rest let her have her 

 way, being doubtless too busy with their pre- 

 sent labours to seek a quarrel with the free- 

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