THE VARIETIES OF FERTILISATION. 313 



worthy. It may or may not be true ; but it is of no value 

 unless thoroughly tested by experiment aud verified. Thus, 

 for example, Mr. Darwin, in speaking of the movements of 

 the stigmatic lobes of Mimulus, says " Mr. Kitchener has 

 ingeniously explained the use of these movements, namely, 

 to prevent the self-fertilisation of the flower." He, however, 

 experimented with this plant, and then discovered that " if 

 insects are excluded the flowers fertilise themselves perfectly, 

 and produce plenty of seed." * 



Again, it has been argued that we are justified in assum- 

 ing that the remarkable adaptations to insects, which are so 

 obvious in many flowers, viust he of some use to the plant, 

 even though we may not be able to discover it. This state- 

 ment, however, is just as much an a priori and deductive 

 assumption as the preceding, and is quite valueless until 

 verified ; and it is only by means of such experiments as Mr. 

 Darwin laboriously carried out, that the real value of inter- 

 crossing and self-fertilisation or other kind of union can be 

 ascertained. Thus, e.g., the Garden Pea is undoubtedly 

 adapted to insects, like other irregular flowers ; but experi- 

 ments proved that " a cross between two individuals of the 

 same variety does not do the least good to the offspring, 

 either in height or fertility." f 



* Ci-oss and Self Fertilisation, p. 64. As another instance of an a 

 priori deduction, Sachs says of Epipactis latifolia, " The flower left to 

 itself does not get fertilised, for the pollen-masses do not spontaneously 

 fall out of the anther; and even if they did, would not come on to the 

 stigmatic surface " (Veg. Phys., p. 796). Mr. A. D. Webster, however, has 

 observed that E. latifolia is very imperfectly fertilised, for, although 

 visited by insects, cross-fertilisation seldom takes place ; that " self- 

 fertilisation by the pollen falling spontaneously on the stigma is not 

 nncommon, as the pollen-masses . . . become friable, and before the plant 

 withers, either spontaneously or by the action of the wind fall on the 

 stigma" {Bot. Gaz., xii., p. 104). 



t i.e., p. 264. 

 29 



