conveyed to the stigma. He was familiar with the
phenomenon, exhibited by numerous flowers, to which Sprengel afterwards
applied the term Dichogamy, expressing the fact that the anthers and
stigmas of a flower often ripen at different times, a peculiarity
which is now recognised as one of the commonest means of ensuring
cross-pollination.

With far greater thoroughness and with astonishing power of observation
C.K. Sprengel (1750-1816) investigated the conditions of pollination of
flowers. Darwin was introduced by that eminent botanist Robert Brown to
Sprengel's then but little appreciated work,--"Das entdeckte Geheimniss
der Natur im Bau und in der Befruchtung der Blumen" (Berlin, 1793); this
is by no means the least service to Botany rendered by Robert Brown.

Sprengel proceeded from a naive teleological point of view. He firmly
believed "that the wise Author of nature had not created a single hair
without a definite purpose." He succeeded in demonstrating a number of
beautiful adaptations in flowers for ensuring pollination; but his work
exercised but little influence on his contemporaries and indeed for a
long time after his death. It was through Darwin that Sprengel's work
first achieved a well deserved though belated fame. Even such botanists
as concerned themselves with researches into the biology of flowers
appear to have formerly attached much less value to Sprengel's work
than it has received since Darwin's time. In illustration of this we may
quote C.F. Gartner whose name is rightly held in the highest esteem as
that of one of the most eminent hybridologists. In his work "Versuche
und Beobachtungen uder die Befruchtungsorgane der vollkommeneren
Gewachse und uber die naturliche und kunstliche Befruchtung durch den
eigenen Pollen" he also deals with flower-pollination. He recognised the
action of the wind, but he believed, in spite of the fact that he
both knew and quoted Kolreuter and Sprengel, that while insects assist
pollination, they do so only occasionally, and he held that insects are
responsible for the conveyance of pollen; thorough investigations
would show "that a very small proportion of the plants included in this
category require this assistance in their native habitat." (Gartner,
"Versucher und Beobachtungen... ", page 335, Stuttgart, 1844.) In the
majority of plants self-pollination occurs.

Seeing that even investigators who had worked for several decades at
fertilisation-phenomena had not ad