Preface xix 



pages which J. H. Fabre, with his usual con- 

 scientiousness, devotes to the exhaustive study 

 of this admirable work ; nevertheless, since the 

 occasion offers, let us listen to his own words, 

 though it be but for a moment and in regard 

 to a single detail : 



' With the oval pieces, the question changes. 

 What model has the Megachile when cutting into 

 fine ellipses the delicate material of the robinia ? 

 What ideal pattern guides her scissors ? What 

 measure dictates the dimensions ? One would 

 like to think of the insect as a living compass, 

 capable of tracing an elliptic curve by a certain 

 natural inflexion of the body, even as our arm 

 traces a circle by swinging from the shoulder. 

 A blind mechanism, the mere outcome of her 

 organization, would in that case be responsible 

 for her geometry. This explanation would 

 tempt me, if the oval pieces of large dimensions 

 were not accompanied by much smaller, but 

 likewise oval pieces, to fill the empty spaces. 

 A compass which changes its radius of itself and 

 alters the degree of curvature according to the 

 exigencies of a plan appears to me an instru- 



