UP IN THE TREES. 209 



trouble, but at the same time, being springy, offers 

 no real obstruction. You see the insect straining 

 to get through, its head moving now this side, now 

 that, as the right or left leg is brought into play. 

 Presently with a jerk the body comes through, and 

 the almost exhausted bee crawls slowly away. 

 But what is that sticking between its shoulders, a 

 conspicuous double mass of yellow on the green ? 

 This is the pollen which has had the opportunity 

 of fixing itself in that position during the bee's 

 struggle to get out, and the foolish insect stumbling 

 into another flower on the same spike, or perhaps 

 on another plant, unwittingly fertilises it, and thus 

 completes the work for which this elaborate appa- 

 ratus was contrived. 



The species of Catasetum are almost as interest- 

 ing, but here it is a large humble-bee, black with 

 yellow bars across the abdomen, which is the 

 fertilising agent. Like the other, it is almost a 

 stranger to our gardens, and appears in a similar 

 manner as soon as the flowers open, even when 

 they are hidden under a dense canopy of foliage. 

 Flying into the flower the bee's proboscis comes 

 in contact with a sensitive, antenna-like appendage 

 connected with the little box in which the pollen 

 is contained. Out jump the pair of pollen masses 

 as if let fly by a spring ; they adhere to the back 

 14 



