290 MR. J. C. WILLIS’S CONTRIBUTIONS TO 
flower and the arrangement of the viscid disc, renders it evident 
that the flower cannot be fertilized by entrance of insects at the 
mouth of the cage. This suggested that the removal, or insertion 
into the stigma, of the pollinia was effected by insects sleding 
down inside the cage. This idea was tested by enclosing the 
flower in a large glass bell-jar and putting a number of large 
humble-bees, such as Bombus hortorum and others, in with it. 
After vainly buzzing round the glass for some time, these began 
to visit the flower, and their actions were carefully watched. 
Sometimes they alighted on the petals and wandered about upon 
them; but others found their way into the bucket by flying 
straight through the large openings between it and the column, 
which appear as if specially constructed for this purpose. The 
bucket contains a great number of juicy hairs, which are pro- 
bably nibbled by bees, as in other orchids; but our native bees 
did not seem to understand how to go to work. Presently, there- 
fore, they tried to return by the way they came. They could 
not, however, fly straight out, as the opening of the bucket itself 
was too narrow for them to spread their wings. They, therefore, 
had to crawl out; and as soon as ever they crawled over the 
edge, they came upon the highly polished surface upon which 
they could get no grip. Sometimes they hung by their hind legs 
for a time; but usually they slipped down at once, slid down the 
cage and out at the mouth. It was quite ludicrous to see the 
way in which the bees “ tobogganed”” down inside the cage ; 
they mostly fell upon the table before they realized what had 
happened. 
These experiments seem to favour the “ sliding” theory; but, 
unfortunately, the pollinia were never removed. The bees usually 
slid down with their backs to the column; and there is no pro- 
jecting point on the back of a humble-bee, so that the projecting 
tongue (c in fig. 7) was never caught. A bee, such as the 
Luglossa mentioned by Darwin, whose tongue is carried under 
its body and projects over its back from behind, would very 
probably remove the pollinia. So also would any bee with any 
projection on its back. Another possible case would be a bee 
with a sharp-pointed abdomen falling tail first. Some of the 
humble-bees experimented on fell tail first, but were too stout to 
put the tail under the rostellum. The curious hollow shape of 
the viscid disc also points to the probable occurrence on the 
visiting insect of some rounded projection (say the tail) which 
will fit it. 
