Bramble-bees and Others 



open at both ends. The arrangements, sav^e 

 for the upper orifice, are the same as before. 

 The cocoons, in some of the tubes, have their 

 heads turned down; others, up; in others 

 again, their positions alternate. The result is 

 similar to what we have seen above. A few 

 Osmias, those nearest the bottom orifice, take 

 the lower road, whatever the direction first oc- 

 cupied by the cocoon; the others, composing 

 by far the larger number, take the higher 

 road, even when the cocoon is placed upside 

 down. As both doors are free, the outgoing 

 is effected at either end with success. 



What are we to conclude from all these ex- 

 periments? First, that gravity guides the 

 insect towards the top, where the natural door 

 is, and makes it turn in its cell when the co- 

 coon has been reversed. Secondly, I seem to 

 suspect an atmospheric influence and, in any 

 case, some second cause that sends the insect 

 to the outlet. Let us admit that this cause 

 is the proximity of the outer air acting upon 

 the anchorite through the partitions. 



The animal then is subject, on the one 

 hand, to the promptings of gravity; and this 

 to an equal degree for all, whatever the storey 

 inhabited. Gravity is the common guide of 



39 



