28 THE FERTILISATION OF FLOWERS, [PART 1, 
explanation of fertilisation, which, erroneous as it was, was not contro- 
verted until the appearance of Sprengel’s book and, afterwards still more 
thoroughly by F. J. Schelver* and August Henschel.2 The researches of 
these botanists showed clearly that in most plants pollination of the pistil 
is impossible or at least improbable without the cooperation of some external 
agent. The last two authors, since they did not ascribe the proper importance 
to insect-visits, were led into the error of denying the sexuality of plants. 
On the other hand, Sprengel has not only rendered the negative service of 
showing, as the others did, how the prevalent conception of the mode of 
fertilisation is directly contrary to the actual relations, but also the positive 
service of removing the last objection to the sexual theory by his theory of the 
adaptation of flowers to fertilisation by insects.* 
2. Even Sprengel notes several instances of incomplete adaptation ; e.g. on 
page 259, “Although the flowers (Lychnis dioica) being nocturnal are not 
adapted for humble-bees, yet these make use of their nectar.” 
3. Perhaps F. G. Kurr has reviewed most thoroughly Sprengel’s observa- 
tions in his book Untersuchungen iiber die Bedeutung der Nektarien in den 
Blumen, which is replete with his own observations and ideas. But even 
this acute observer 4 lets us clearly trace how his ignorance of the advantage 
of cross-fertilisation prevented him from agreeing with Sprengel’s explanations, 
and how, along with Sprengel’s theories, he rejected his correct observations 
(e.g. in the case of Campanula) in order to cling to old errors. 
Severin Axell, in his above-mentioned work, cites the following later 
botanists who rejected Sprengel’s discoveries ; “'Treviranus,> in upholding the 
sexuality of plants against Henschel, denies altogether that the organs of the 
two sexes mature at different times, and declares that the pollen and the stigma 
always ripen simultaneously ; Schultz-Schultzenstein ® attacks Sprengel, and 
charges him with false statements; De Candolle’ asserts: ‘M. Conrad 
Sprengel a cherché 4 développer ses idées, plus fondées, je le crains, sur des 
théories métaphysiques que sur la simple observation des faits;’ Mikan 
criticises him for his description of the apparatus for fertilisation in the violet ; 
even Robert Caspary says, ‘ quod censeo, non injuste dici potest, inter omnes 
illas Sprengelii observationes, quas certissimas profert, quo modo insecta flores 
fecundent, ne unam quidam esse, ex qua certe concludi possit, nullo alio modo’ 
flores fecundari quam auxiliis insectorum.’ Robert Brown alone, in his 
well-known paper (114) on the fertilisation of Asclepiadacee and Orchidaceae, 
confirmed the accuracy of Sprengel’s statement that the aid of insects is 
necessary for the fertilisation of these plants, although he, like Sprengel, 
failed to notice that here cross-fertilisation occurs and not self-fertilisation.” 
Just as, according to these extracts, most botanists reviewed onesidedly 
the weakness of Sprengel’s theory, and threw overboard the good along with 
the defective ; so, with equal onesidedness, Delpino and Severin Axell have 
1 Kritik der Lehre von den Greschlechtern der Phlanzen (Heidelberg : 1812), 
2 Von der Sexualitét (Breslau : 1820). 
3 Of. Severin Axell, “ Om det fargade hyllets betydelse for vdaten,” Bot, Notiser 
Tredje haftet, 1868. 
4 Loe. cit. pp. 188, 139. 
5 Die Lehre vom Geschlechte der Pflanzen (Bremen: 1822), 
6 Die Fortpflanzung und Ernihrung der Pflanzen (1828). 
7 Organogruphie végétale, i. p. 538 (Paris: 1827). 
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