THE SELF-FEKTILISATION OF PLANTS. 
3 
then permanently secured in their combination, and the pendu- 
lum comes to rest. 
Such I believe to be the case with the question before us ; 
for I think I can show that Darwin’s aphorism is wrong in its 
extreme form, if not altogether; and the object of the present 
paper is to endeavour to combine the twin truths which underlie 
the cross and self-fertilisation of plants. 
Mr. Darwin’s works have gone far to strengthen the belief 
that intercrossing is absolutely necessary for plants ; and that 
if self-fertilisation be continued for lengthened periods the plant 
tends to degenerate and thence to ultimate extinction. This I 
believe to be absolutely false. Indeed, so strong is the general 
belief in the value of intercrossing, that self-fertilisation is kept 
quite in the background, if at all alluded to, by writers on 
this subject ; so that flowers are now usually classed either as 
“ entomophilous,” i.e ., adapted to insect agency, or else as “ ane- 
mophilous ” or wind-fertilised. 
When Mr. Darwin examined Orchids and wrote his excellent 
book on their fertilisation, he was struck with the singular ex- 
ception of the “ Bee-orchis” ( Ophrys apifera ), which is so con- 
structed as to fertilise itself ; and yet this plant is one of the 
most abundant of orchids, a vigorous grower, and shows no signs 
of degeneracy at present. Another case, amongst many others 
mentioned in his 66 Cross and Self-fertilisation of Plants,” is that of 
the garden pea, which is constantly self-fertilised in this country, 
and yet the papilionaceous corolla is manifestly and specially 
adapted to insects. Mr. Darwin alludes to Mr. A. Knight’s varie- 
ties, originally obtained by crossing, as having lasted for upwards 
of sixty years, by self-fertilisation alone ; and the inference in both 
cases is, that the effects of crossing — in the ancestral form of the 
Bee-orchis, which doubtless required it, and in the artificial 
crossings made by Mr. Knight — have lasted, to the present day 
in the first case, and for sixty years in that of the pea. 
Moreover, since a great number of plants are now discovered 
to be in the habit of setting seed, and that too very freely, with- 
out insect aid, a further generalisation has been made, that not 
only were they originally crossed, and the good effects have 
lasted till now, that is to say, for practically an indefinite series 
of ages ; but that they must be occasionally crossed again, or 
they will inevitably die out in time. 
Now it must be carefully noted that these generalisations are 
entirely subjective or a priori inferences, based upon the 
assumed necessity of crossing ; that assumption being itself 
based upon the vast number of adaptations to insect agency 
which exist ; but the fact that self-fertilisation is really of wider 
extent in the vegetable kingdom is ignored. On the other 
hand, the belief appears to be generally held that many flowers 
