462 THE FERTILISATION OF FLOWERS. [PART III. 
pollen lodged, and in the mechanism for scattering the pollen and 
for guiding the insect’s proboscis. 
a. The protection of the anthers. In Odontites lutea the 
anthers protrude from the flower, as in Veronica; in Odontites 
serotina they are only slightly covered by the upper lip, while they 
are entirely covered by it in #. officinalis ; in the three others they 
are completely inclosed in the hood of the upper lip. 
b. The pollen-receptacles. In the two species of Odontites 
and in Huphrasia officinalis each anther-lobe forms a separate 
receptacle opening at the apex; in O. lutea all the anthers are 
separate ; in O. serotima they are connected posteriorly by matted 
hairs; in &. officinalis their edges cohere. In Melampyrum, 
Rhinanthus, and Pedicularis, their edges are closely united so as to 
form a single, more or less distinctly four-chambered receptacle. 
c. The shedding of the pollen.. In QO. lutea and O. serotina 
the anthers must be touched in order to shed their pollen; in 
O. lutea each must be touched separately, but in O. serotina 
one touch is communicated to all. In LZ. officinalis the lower 
anthers, in Melampyrum all of them, bear sharp appendages which 
point downwards, and which, when touched, cause the pollen to 
fall out. In Rhinanthus, the pollen-receptacle is opened by 
pushing apart the filaments. In Pedicularis, the edges of the 
hood which incloses the pollen-receptacle are separated by a 
complex system of levers, and the pollen-receptacle then opens. 
In all, except O. lutea, hairs directed downwards (either from the 
edges of the anthers or from the filaments) prevent the pollen 
being scattered at the sides, 
d. The path of the bee’s proboscis. In 0. lutea and L. officinalis 
the path is only marked out by the entrance of the tube ; but in 
O. lutea the bee’s proboscis cannot fail to come in contact with one 
or other of the anthers, and in J. officinalis with their appendages. 
In the other four species sharp points on the filaments or on the 
edges of the upper lip cause the bee to insert the tip of its 
proboscis just in such a position that it may first touch the stigma 
and then dust itself with pollen. 
In regard to all four characters Odontites lutea stands lowest, 
and Pedicularis silvatica highest. 
Cross-fertilisation in case of insect-visits is insured in all the 
six species by the stigma being touched in all or most flowers 
by the same part of the insect which is immediately afterwards 
dusted with pollen. In three species out of the six, two forms of 
flowers occur, of which one is sparingly visited by insects and in 
