THE OSMIiE 255 



The other rear tubes, the minority, whose diameter is 

 about 6 millimeters,^ contain sometimes only females and 

 sometimes females at the back and males towards the 

 opening. One can see that a tube a trifle wider and a 

 mother slightly smaller would account for this difference 

 in the results. Nevertheless, as the necessary space for 

 a female is barely provided in this case, we see that the 

 mother avoids as far as she can a two-sex arrangement 

 beginning with males and that she adopts it only in the 

 last extremity. Finally, whatever the contents of the 

 small tube may be, those of the large one, following upon 

 it, never vary and consist of females at the back and 

 males in front. 



Though incomplete, because of circumstances very 

 difficult to control, the result of the experiment is none 

 the less very remarkable. Twenty-five apparatus contain 

 only males in their narrow gallery, in numbers varying 

 from a minimum of one to a maximum of five. After 

 these comes the colony of the large gallery, beginning 

 with females and ending with males. And the layings 

 in these apparatus do not always belong to late summer 

 or even to the intermediate period: a few small tubes 

 contain the earliest eggs of the entire swarm. A couple 

 of Osmiae, more forward than the others, set to work 

 on the 23rd of April. Both of them started their laying 

 by placing males in the narrow tubes. The meager sup- 

 ply of provisions was enough in itself to show the sex, 

 which proved later to be in accordance with my antici- 

 pations. We see then that, by my artifices, the whole 



1 .234 inch. — Translator's Note. 



