THE PER TILISA TION OF FL WERS. 3 1 9 



epistles to " Mr. Editor " by way of inquiry whether or not the 

 sulphureous shower is a portent or grave omen of coming disaster or 

 impending peril. 



The phenomena of fertilisation just detailed, take place in our 

 primrose, as in all ordinary plants ; but whilst there exists a uni- 

 formity in the details of this process, there is also found a literally 

 amazing variety in the fashions whereby pollen is conveyed to the 

 stigma of the pistil. Once placed in the natural position for fertili- 

 sation, the growth of the pollen-tube follows as a matter of course. 

 But the means whereby the pollen reaches the stigma, and the 

 various fashions in which it may gain its ultimate position on the pistil, 

 constitute features in which are bound up some of the most important 

 issues of plant existence. To rightly comprehend the bearing of fertili- 

 sation, a glance at our wallflower (Fig. 205), primrose (Fig. 208), fox- 

 glove (Fig. 206), or buttercup will suffice as a starting-point for further 

 investigation. Within the primrose and the buttercup are situated, as 

 we have seen, the two sets of organs stamens and pistil necessary to 

 secure the production of seed and the continuance of the race. Hence 

 it might form a very natural and reasonable inference, that the pollen 

 from the numerous stamens of a buttercup flower should be used to 

 fertilise the ovules of the pistil of that flower. Such a process that 

 in which a flower's own pollen is used to fertilise its own ovules is 

 termed " self- fertilisation." Looking at the vast 'majority of our 

 flowers and plants, which possess each a perfect array of stamens 

 and pistil, the normal course of things seems strongly suggestive of 

 self-fertilisation. Hence, in the early days of botany, self-fertilisation 

 was undoubtedly believed to be the rule of nature. Now, there can 

 be no question whatever that " self-fertilisation " does occur in nature, 

 but there is as little doubt that it is the exception, and not as 

 botanists from the days of Linnaeus well-nigh to our own day have 

 maintained the rule, of plant life. There can be little doubt, for 

 instance, that many small species of the buttercup order (Ranuncu- 

 lacecs e.g. Ranunculus hederaceus) are self-fertilised, because we find 

 the stamens to arch over the pistil, and to shed their pollen on the 

 carpels. I n Agrimonia, in the same order, the stamens, at first curved 

 outwards, curve inwards, so as to bring the pollen within easy reach 

 of the stigmas. So, also, in a species of Malvaceae (Malva rotundi- 

 fo/ta), Miiller has demonstrated that this plant is self-fertilised, since 

 stigmas and anthers actually intertwine, and are thus placed in the 

 most favourable position for the fertilisation of the ovules. Some 

 species of Geraniacea (e.g. Geranium pusilluni) are self-fertilising 

 likewise ; and many flowers belonging to the rose tribe (fiosacea], such 

 as Potentilla, fertilise themselves. 



It is a remarkable fact that in certain plants (e.g. many violets ; 

 Lamium amplexicaule ; Oxalis, &c.) very small, inconspicuous, and 



