574 
Insects and Flowers 
Fig. 765.—Honey-bee at 
Asclepias - flowers, with 
legs still fast in a stigmatic 
chamber of the flower last 
visited. (After Stevens; 
natural size.) 
“Each pollen-sac contains a compact mass of pollen-grains which never 
become separated from one another, and so constitute what is termed a 
pollinium. The two contiguous pollinia of adja¬ 
cent anthers are united by horny rods which con¬ 
verge upward and join with a horny dark body 
known as the corpusculum, which is hollow and 
has a slit along its outer face. This slit is rel¬ 
atively broad at the bottom, and tapers toward 
the top, thus forming a clip in which the feet of 
the insects get caught. Between each pair of 
anthers there is a deep recess closed by two vertical 
lips which stand wider open at the bottom than 
at the top, and the recess also narrows at the top. 
The opening between the lips at the top stands 
exactly beneath the slit in the corpusculum. 
“The surface of the flower is slippery, so that 
when a bee, for instance, visits it, a good foothold 
is not obtained until the bee slips its foot into the 
recess between the anthers, termed the stigmatic 
chamber. Having obtained a foothold, the bee 
thrusts its sucking-apparatus into the hollow nectar- 
receptacle and obtains the nectar which has invited it to the flower. When the 
bee, however, seeks to go to another flower, its foot slips upward and becomes 
caught in the slit in the corpusculum. A struggle 
now ensues which usually results in the bee pull¬ 
ing the two pollen-masses, united to the corpus¬ 
culum, through the narrow slits at the tops of the 
pollen-sacs; and thus laden, it seeks another flower, 
and there slips its foot, together with the pollen- 
masses, into the stigmatic chamber. 
“Now when the bee attempts to leave the flower, 
the pollen-masses become tightly wedged at the 
narrow apex of the chamber, and a hard pull is re¬ 
quired to break them loose from the foot. Finally, 
as the foot is being drawn from the stigmatic 
chamber it catches into the corpusculum directly 
above and pulls out a second pair of pollen- 
masses. Thus the bee goes from flower to flower 
and from plant to plant, repeatedly pulling pollen- 
masses from their sacs and depositing them in 
the stigmatic chamber. Fig. 765 is from a photograph of a honey-bee 
gathering nectar from Asclepias-flowers. One of the hind legs is still 
Fig. 766.—Cabbage-butter¬ 
fly caught by legs in 
corpuscula of two Ascle¬ 
pias - flowers. (After 
Stevens; natural size.) 
