Branible-bees and Others 



quite content to know that I do not know, 

 which at least spares me many vain lucubra- 

 tions. And so I do not know how the Osmia, 

 in the dense darkness of her tunnel, distin- 

 guishes between a live cocoon and a dead co- 

 coon of the same species; and I know just as 

 little how she succeeds in recognizing a strange 

 cocoon. Ah, how clearly this confession of 

 ignorance proves that I am behind the times! 

 I am deliberately missing a glorious oppor- 

 tunity of stringing big words together and ar- 

 riving at nothing. 



The bramble-stump is perpendicular, or 

 nearly so; its opening is at the top. This is 

 the rule under natural conditions. My arti- 

 fices are able to alter that state of things: I 

 can place the tube vertically or horizontally; 

 turn its one orifice either up or down; lastly, 

 I can leave the channel open at both ends, 

 which will give two outlets. What will hap- 

 pen under these several conditions? That is 

 what we shall examine with the Three- 

 pronged Osmia. 



The tube is hung perpendicularly, but 

 closed at the top and open at the bottom; in 

 fact, it represents a bramble-stump turned up- 

 side down. To vary and complicate the ex- 



35 



