SELF-FERTILIZATION OF PLANTS. 335 
These observations led me to see a special correlation between the pistil and the other 
floral whorls. Hence, if a flower be proterandrous, whatever may tend to lessen the 
energy of growth of these outer whorls tends at the same time to direct it into the pistil, 
which now advances, and is able to develope simultaneously with the Manon; and so 
self-fertilization is the result. 
Now, on referring to the headings 4, i. and 4, iv., it will be seen that these two causes 
of self-fertilization would seem due to the reduction or arrest of the corolla. Such, how- 
ever, may not be the sole cause, but only the index of an impaired condition or, at least, 
a lowering of the general vitality of the plant. Thus the withering of the corolla and 
part of the andreecium of Tradescantia implied a want of energy in those parts, in 
eonsequence of the lowness of the autumn temperature. Similarly, the partial arrest 
or complete loss of colour in the corolla is another indieation of lessened vegetative 
vigour, just as albinism in the animal kingdom indicates the same fact. There is reason 
to believe such flowers are more inclined to be self-fertile than others, as they are also 
more permanent. It must be remembered that while feebleness of constitution may 
induce self-fertility, the converse is not true. Self-fertility does not induce feebleness. 
If this be the true rationale, we see that self-fertilization and self-sterility are resolved, 
so far at least, into a simple question of compensation, which, in turn, is a question of 
nutrition; and it has nothing to do with any supposed injuriousness whatever. In fact 
-it is an absolute loss (and therefore an “injury ") to a plant to be self-sterile, for its 
facility for propagating is largely, if not entirely, checked *. This is notably the case 
with the Scarlet Runner (Gard. Chr. vol. x. p. 561). 
Though I agree with Mr. Darwin, “ that the inefficiency of a plant's own pollen [phy- 
siologically] is in most cases an incidental result [due to differentiation], and has not been 
specially acquired for the sake of preventing self-fertilization," I cannot agree with him 
in drawing a different conclusion for morphologically self-sterile plants; for he adds :— 
* On the other hand, there can hardly be a doubt that dichogamy ... . that the hete- 
rostyled condition of certain plants, and that many mechanical structures, have all been 
acquired, so as both to check self-fertilisation and to favour cross-fertilisation.” And 
yet he proves that when plants lose their dichogamy they regain self-fertility, which 
Mr. Darwin then recognizes as an advantage to the plant; while elsewhere he says, “ it 
is difficult to avoid the suspicion that self-fertilisation is in some respects advantageous.” 
My impression is that flowers were primordially hermaphrodite, inconspicuous, and self- 
fertile. If I might venture further into the regions of speculation, I would suggest, as 
a feasible hypothesis, that insects having been attracted to the juicy tissues of such 
flowers, by perpetually withdrawing fluids have thereby kept up a flow of the secretion, 
which has increased, and so developed into glandular and regularly secreting organs. 
The mere puncture and lesion caused by an insect would not of itself be hereditary, just 
as galls do not form spontaneously ; still even with them there may be, for all we know, a 
predisposition to form them, and they may be now perhaps much larger than they were 
* Since this paper was read, one by Mr. Meehan has been printed in the Journal of the Linn. Soc., in which he 
shows how Wistaria, though it never sets seeds, when “trained,” yet, when grown as a “ tree," does at expend ita 
energy in forming long branches, and consequently fruits abundantly. 
8a 2 
