The Leaf-cutters 



into cells that will remain empty; she closes 

 with a thick plug reeds containing nothing. 

 Thus is the little strength of her last hours 

 exhausted in vain work. The other build- 

 ing Bees behave likewise. I see Anthidia 

 laboriously providing numerous bales of cot- 

 ton to stop galleries wherein never an egg was 

 laid; I see Mason-bees building and then re- 

 ligiously closing cells that will remain unvic- 

 tualled and uncolonized. 



The long and useless barricades then be- 

 long to the last hours of the Megachile's life, 

 when the eggs are all laid; the mother, whose 

 ovaries are exhausted, persists in building. 

 Her instinct Is to cut out and heap up pieces 

 of leaves; obeying this impulse, she cuts out 

 and heaps up even when the supreme reason 

 for this labour ceases. The eggs are no 

 longer there, but some strength remains; and 

 that strength is expended as the safety of the 

 species demanded in the beginning. The 

 wheels of action go on turning in the absence 

 of the motives for action; they continue their 

 movement as though by a sort of acquired 

 velocity. What clearer proof can we hope to 

 find of the unconsciousness of the animal 

 stimulated by instinct? 



247 



