18 THE FERTILISATION OF FLOWERS. [PART I, 
become here and there prevalent of the significance of cross- 
fertilisation; and also for attempting to arrange all the floral 
mechanisms of Phanerogams in a series, according to their natural 
development from less perfect to more perfect forms. 
The first impulse to the new investigation of flowers had been 
given by Darwin’s notion of a general law that no organised being 
fertilises itself for an unlimited number of generations, or, as 
Darwin put it, that nature abhors perpetual self-fertilisation. And 
it was natural that those investigators who worked upon the lines 
laid down by Darwin should look upon the contrivances that were 
favourable to cross-fertilisation and unfavourable to self-fertilisation 
as so many proofs of the truth of Darwin’s conjectural law. But 
they neglected to consider those flowers which frequently or 
regularly fertilise themselves; or, if such flowers forced them- 
selves upon their notice, they were looked upon as isolated excep- 
tions, and self-fertilisation was considered, in spite of them, as 
throughout injurious to plants. For instance, Hildebrand in 1867 
says: ‘In most plants self-fertilisation is avoided by special 
contrivances or even rendered impossible, or if it does take 
place it is at least injurious;” and in 1869 he tries to prove 
“the law of the avoidance of self-fertilisation,’ and to treat as 
isolated exceptions Calccolaria pinnata and Morina elegans, in 
which he had found self-fertilisation to take place regularly when 
insect-visits fail. Similarly, in Delpino’s writings until 1869 
the idea recurs in many places, quite definitely, that “nature in 
general abhors self-fertilisation,”! while Darwin had only spoken of 
perpetual self-fertilisation. Now Axell justly showed that this 
conception entertained by Hildebrand and Delpino was unfounded, 
for he brought forward in opposition to it the facts that in many 
flowers self-fertilisation inevitably takes place in default of insect- 
visits, and that he himself had proved by experiment in many 
cases that such self-fertilisation results in the production of good 
seed; further, that many aquatic plants, which under ordinary 
circumstances expand their flowers at the surface of the water and 
are cross-fertilised by the wind or by insects, remain closed and 
submerged when the water is unusually high, and in such cireum- 
stances fertilise themselves and produce seeds which propagate the 
species; and finally, that many terrestrial plants, with irregular 
flowers which render self-fertilisation impossible, produce, instead 
of these or along with these, other flowers of simple structure 
1 For instance, in No. 177, p. 55, “L’antipatia che ha Ja natura per le nozze 
consanguinee ” (1869). 
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