100 THE FERTILISATION OF FLOWERS. [PART III. 
period, yet it is so regularly fertilised by that one, that it has quite 
lost the power of self-fertilisation ; while /wmaria officinalis, though 
it might be fertilised by very many kinds of bees that are abundant 
while it flowers, is so little visited that it is forced as a rule to 
reproduce by self-fertilisation. I have repeatedly noticed how very 
seldom Fumaria officinalis is visited by insects, and have observed 
that notwithstanding almost every flower has borne fruit. I have 
also found that during continued rainy weather which keeps every 
bee away, F”. officinalis is still fully fruitful, and I cannot therefore 
doubt that it makes the fullest use of its power of self-fertilisation. 
The same holds good with regard to Fumaria capreolata, L., 
and /. parviflora, Lam., which on the whole agree, according to 
Hildebrand, with / oficinalis in their mechanism of fertilisation, 
but have lost the elasticity of the hood, probably through long 
disuse. , 
In Fumaria spicata, L., on the other hand, the structure of the 
flower resembles, according to Hildebrand, that of Corydalis lutea 
and C. ochroleuca. The column, after once emerging from the 
hood, springs up, owing to the tension of the upper stamens, and 
buries itself in a depression in the upper petal. This species is 
also fertile to its own pollen. 
Fumaria capreolata, var. pallidiflora, has this remarkable 
peculiarity, first mentioned by Moggridge, that its flowers, which 
are at first almost white, assume a conspicuous pink or even 
carmine tint after fertilisation. A similar change of colour occurs 
in Lantana, Weigelia rosea, Ribes aureum, R. sanguineum, and 
many other flowers which are fertilised by the more intelligent 
insects (bees or Lepidoptera). The insects are attracted from a 
distance by the bright colours of the older flowers, and they learn 
to distinguish very quickly between these and the less conspicuous 
younger flowers which alone contain treasure for them ; while the 
less intelligent insects, useless in these cases for the work of 
fertilisation, betake themselves chiefly to the more showy flowers 
(74, 309, 530, 575, 590, L.). 
Ord. CRUCTFERA. 
27, NASTURTIUM SILVESTRE, R. Br.—At the base of the flower, 
between every two stamens, there is visible a green fleshy gland, 
which secretes a drop of honey. The anthers of the four longer 
stamens are on a level with the stigma, the other two lie somewhat 
deeper; all remain turned towards the middle of the flower. In 
