Instinct and Discernment 



therefore that, witrhout the intervention of 

 man, involuntary in the vast majority of 

 cases and deliberate only on the experi- 

 menter's part, the Osmia would hardly ever 

 find a reed-stump suited to the installation 

 of her family. It is to her a casual ac- 

 quisition, a home unknown to her race be- 

 fore men took it into their heads to cut 

 reeds and make them into hurdles for dry- 

 ing figs in the sun. 



How did the work of man's pruning- 

 knife bring about the abandonment of the 

 natural lodging? How was the spiral 

 staircase of the Snail-shell replaced by the 

 cylindrical gallery of the reed? Was the 

 change from one kind of house to another 

 effected by gradual transitions, by attempts 

 made, abandoned, resumed, becoming more 

 and more definite in their results as genera- 

 tion succeeded generation? Or did the 

 Osmia, finding the cut reed that answered 

 her requirements, install herself there 

 straightway, scorning her ancient dwelling, 

 the Snail-shell? These questions called for 

 a reply; and they have received one. Let 

 us describe how things happened. 



Near Serignan are some great quarries 

 of coarse limestone, characteristic of the 

 miocene formation of the Rhone valley. 

 169 



