FECUNDATION. 187 
In the Orchidacee, in which the structure of the pollen is very 
peculiar, the intervention of insects appears favourable, but not 
indispensable, to fecundation. 
When the doctrine of sexual organs in vegetables was first 
made public by Linnzus, it was disputed by many. Conrad 
Sprengel, a patient observer, watched during many long hours for 
the instant when an insect, settling on a flower, should suck out 
its sweet-smelling juices and deposit the pollen grains on the 
stigma of the flower. Sprengel succeeded in this way in verifying 
a natural fact, interesting without doubt, but it was no argument 
against the doctrine of Linnzeus; nor did the work he published 
in which all the arguments against the sexual system in plants 
were reproduced, at all change the current of the new ideas. 
In certain climates the Aumming-birds are useful auxiliaries in 
the fecundation of flowers. The hand of man, also, frequently 
intervenes in practising artificial fecundation—bringing in this 
way the most convincing of all arguments in favour of the doctrine. 
We may instance as an example the fecundation of the Date-tree, 
which is practised in Algeria and all over the East, as related by 
a botanist who has studied the subject on the spot :—“ Towards 
the month of April,’ says M. Cosson, “the Date-tree begins to 
flower, and then artificial fecundation is practised extensively. 
The male spathes are opened at the time when a sort of crackling 
is produced under the finger, which indicates that the pollen of 
the flowers in the cluster is sufficiently developed, yet has not 
escaped from the anthers; the cluster is then divided into frag- 
ments, each containing seven or eight blooms. Having placed the 
fragments in the hood of his durnous, the workman climbs with 
marvellous agility to the summit of the female tree, supporting 
himself by a loop of cord passed round his loins, and at the same 
time round the trunk of the tree. He glides with great address 
between the stalks of the leaves, the strong and sharp thorns of 
which render the operation rather dangerous ; and having split 
open the spathe with a knife, he slips in one of the fragments, 
which he interlaces with the branches of the female cluster, the 
fecundation of which is now made certain.” 
Another phenomenon sometimes exhibits itself at the time of 
flowering ,which bears an intimate relation to fecundation; this is the 
