390 REV. GEORGE HENSLOW ON THE 
are for the most part humble and insignificant weeds, it is true, and are probably de- 
graded forms of conspicuous and formerly intererossed plants; but, as they exist now, 
there are no perceptibly evil effects or injuriousness (using these words in their ordinary 
sense) at all attributable to self-fertilization. On the contrary, if we regard, with Mr, 
Darwin, propagation as the one end and aim of plant life, then self-fertilization can 
only be regarded as an inestimable boon to the plant. 
That self-fertilization is in some way injurious appears to be the view of Sir J. D. 
Hooker; for he says, in alluding to different methods of fertilization :— 
** Tn all these instances the double object of Nature may be traced; for self-impregnation (or * breed- 
ing in’), while securing identity of form in the offspring, and hence hereditary permanence, at the same — — 
time tends to weakness of constitution, and hence to degeneracy and extinction” *, 
He does not state on what grounds this opinion is based. 
16. Self-fertilized plants may be absolutely much more productive than flowers 
dependent upon insects. 
The latter may fail in particular seasons, and may be entirely wanting if a plant 
migrate beyond the range of its habitual visitor. Under either of these alternatives the 
self-fertilizing plants would prove to be the best off. It is well known, for example, ` 
how clover-seed is dependent upon the visits of Humble-bees, and how a field may ` 
largely fail in inclement weather if these insects do not visit it. Moreover, humble-bees ` 
often do more harm than good, by perforating the tubes of flowers instead of entering ` 
the corolla. 
Plants habitually crossed in Hil native country may quite fail to secure any insects i a 
to accomplish the process elsewhere, as the Scarlet Runner in Nicaragua; yet if they K 
acquire self-fertilizing powers they will at once become independent of them. Such a 
appears to have been the case in this country under cultivation with Pisum sativum, ` 
Phaseolus multiflorus, and Canna Warscewiczi. If they do not do so, and no insects ` a 
visit them in their new abode, they must inevitably die out. On the other hand, there ` 
are many conspicuous and (but probably more) inconspicuous flowers which, being both 
independent of insects and highly self-fertile, are quite able to maintain their existence — ` 
and propagate freely wherever they may happen to be located. Now the above appears — 
to be actually the case, as far as negative evidence on the one hand, i. e. the absence of 
our intercrossing plants, and positive evidence on the other, i. e. the presence of our self- 
fertilizing plants in foreign countries, tends to prove it. 
A large number of European plants are very widely dispersed, not only ione am 
the northern hemisphere, but in the southern as well. And if we, for convenience, limit ` ` 
our observations to the distribution of British plants, what we find is, that they are ` 
certainly mostly, and probably all, self-fertilizing or wind-fertilizing plants. At all events, ` 
with rare exceptions, they are all inconspicuous plants; and experience leads me to con- : 
clude, I think justly, that all such are habitually self-fertilized or anemophilous. It is a _ 
remarkable fact that wherever there are two or more species to a genus, one or more of : 
which are conspicuous, and the other or others inconspicuous, it is a rule that the latter 
only have succeeded in establishing themselyes in foreign countries. | SCH 
Ce EE any otis Tie zd x. | cp Kan Ge 
