The Mason-Wasps 



worthlessness of a site and knows how to 

 sprinkle it with cells according to the size 

 and shape of the space at its diposal. Here, 

 slight industrial variations are necessary 

 and inevitable; and the insect excels in them 

 without any apprenticeship, as the experi- 

 ment with the Osmia born in the quarries 

 has proved. 



Animal resources have a certain elasticity 

 within narrow limits. What we learn from 

 the animals' industry at a given moment is 

 not always the full measure of their skill. 

 They possess latent powers held in reserve 

 for certain emergencies. Long generations 

 can succeed one another without employing 

 them; but, should some circumstance re- 

 quire it, suddenly those powers burst forth, 

 free of any previous attempts, even as the 

 spark potentially contained in the flint 

 flashes forth independently of all preceding 

 gleams. Could one who knew nothing of 

 the Sparrow except the nest under the eaves 

 suspect the ball-shaped nest at the top of a 

 tree? Would one who knew nothing of 

 the Osmia save her home in the Snail-shell 

 expect to see her accept as her dwelling a 

 stump of reed, a paper funnel, a glass tube? 

 My neighbour the Sparrow, impulsively 

 taking it into his head to leave the roof for 

 174 



