448 THE FERTILISATION OF FLOWERS. [PART III. 
an insect with a proboscis less than 4 mm. long can reach the 
honey by thrusting its head into the wide part of the tube. 
The upper lip forms a vaulted roof over the stamens; it shelters 
the honey at the base of the tube from rain, and prevents an in- 
sect's proboscis from being thrust in above the stamens, as was 
possible in Odontites serotina. The three-lobed under-lip forms a 
convenient landing-place for the smaller visitors, and affords foot- 
hold for the forelegs of larger ones. An orange spot on the under 
lip, another at the entrance of the tube, and dark violet lines con- 
verging towards the mouth on both upper and lower lips, serve as 
Fic. 154.—Euphrasia officinalis, L. 
1.—Flower of the small-flowered form, seen from the front (x 7). . 
2.—The two stamens of the right half of the flower, from the outer side. 
3.—Ditto, more magnified, from the inner side. ; . 
4.—Flower of the large-flowered form, just after ima from the side (x 34). A 
a, stigma; b, upper half of the upper anther ; c, lower half of the upper anther connected with 
the upper half of the lower; d, lower half of the lower anther ; e, style. 
pathfinders. As in Odontites serotina, the pollen is smooth and 
powdery, and falls on the head or proboscis of the visitor; but the 
details of the process by which the pollen is scattered are unlike 
those of the former species. While in Odentites serotina the 
anthers are only held together posteriorly by matted hairs, in 4. 
officinalis the lower anther-lobe of the upper stamen on each side 
coheres with the upper anther-lobe of the lower; and the two 
superior anthers further cohere firmly together. Another peculi- 
arity is directly connected with this. While in Odontites serotina 
