176 MR. C. DARWIN ON THE SEXUAL RELATIONS OF 
sides, to that side where the structure of the flowers allows the 
easiest access to it, as in Zythrum, Papilionaceous flowers, and 
many others. The rule consequently is that when the pistil and 
stamens are bent, the stigma and anthers are brought into the 
pathway towards the nectary. There are a few cases which seem 
to be exceptions, but they are not so in truth: for instance, in the 
Gloriosa lily, the stigma of the grotesque and rectangularly bent 
pistil is brought, not into the pathway from the open air towards 
the nectar-secreting recesses of the flower, but into the circular 
route from one nectary to the other; in Scrophularia aquatica 
the pistil is bent downwards from the mouth of the flower, but 
it thus strikes the pollen-dusted breasts of the wasps which 
habitually visit these ill-scented blooms. In the above rule we seë 
one more instance of the supreme dominating power of insects 
over all the minor structural details of flowers, especially of those 
which have irregular corollas. Flowers which are fertilized by 
the wind must of course be excepted, but I do not know of a 
single instance of an irregular flower which is fertilized or crossed 
by this means. 
I have delayed too long on these points, but I must allude to 
one other. We have seen that the three pistils of different 
lengths have each two half-dozen sets of stamens of correspond- 
ing length. When bees suck the flowers, the longest stamens, 
bearing the green pollen, rub against the abdomen and the inte- 
rior sides of the posterior legs, as does likewise the stigma of the 
long-styled form. The stamens of middle length and the stigma 
of the mid-styled form rub against the under side of the thorax 
and between the front pair of legs. The shortest stamens and 
the stigma of the short-styled form must rub against the pro- 
boscis and chin; for the bees in sucking insert only the front of 
their heads into the calyx. On catching bees, I observed much 
green pollen on the inner sides of the hind legs and on the abdo- 
men, and much yellow pollen on the under side of the thorax. 
There was also pollen on the chin, and, it may be presumed, on 
the proboscis, but this was difficult to observe. I had, however, 
independent proof that pollen is carried on the proboscis; for in 
a protected short-styled plant (which produced only two cap- 
sules) one small branch was accidentally left during many day " 
pressing against the fine net, and bees were seen inserting their 
probosees through the meshes, and in consequence numerous 
capsules were formed on this one small branch. From these 
several facts it follows that insects would chiefly carry to the 
