[220]

Temperature under Skylight

[table not transcribed]

[220v]

57

668

Chap. E 10

they are now but little visited by insects. In either case they must also have acquired or retained a high degree of self-fertility.) (As soon as self fertility become in any way advantageous to a species, it became from any cause advantageous to a species to have its capacity for self-fertilisation increased, there is little difficulty in believing that this could readily be effected; for three cases of plants varying in such a manner as to be more fertile with their own pollen than they originally were, capacity might have been increased; for three such cases occurred in the course of my few experiments, namely, with Mimulus, Ipomoea, and Nicotiana.

There is even some We have also seen reason to suspect, as we have seen, that self-fertilisation is in some peculiar manner beneficial to certain plants; but if this be really the case, such benefits thus thus derived is are far more than counterbalanced by a cross with a fresh stock or with a slightly different variety.

Plants which are highly self-fertile can certainly propagate themselves by this process for many generations, as we see Nor is there any reason to doubt that many kinds of plants are capable under favourable circumstances of propagating themselves for very many generations by self-fertilisation. This is occurred with the varieties of Pisum sativum and of Lathyrus odoratus under culture which are cultivated in England, and with Ophrys apifera and a few some other plants under in a state of nature. Nevertheless, most or all of these plants retain structures in an efficient state which cannot be of the least use excepting