CHAP. XIL GENERAL RESULTS. 44l 



self-fertilised. But the evidence appears to me in- 

 sufficient, until it can be shown that such flowers are 

 not visited during the night by any of the innumerable 

 kinds of small moths. From the simple fact of these 

 small flowers expanding, and from some of them 

 secreting nectar, it seems probable that they are at 

 least occasionally visited and intercrossed by nocturnal 

 insects. It is much to be desired that some one should 

 cross and self-fertilise such plants and compare the 

 growth, weight, and fertility of the offspring. The 

 Rev. G. Henslow* remarks that the plants which have 

 spread the most widely through the agency of man into 

 new countries, and have there grown most vigorously, 

 commonly bear small and inconspicuous flowers; and, 

 as he assumes that these are always self-fertilised, 

 he infers that this process cannot be at all injurious 

 to plants. He believes that " as long as a plant is 

 " self-fertilising, it remains in the same condition, and 

 " retains its average standard, but does not degenerate 

 "in any way. It cannot be benefited, as it cannot 

 " introduce anything new into its system, so long as it 

 " lives in the same place ; hence its results are negative. 

 "If, however, self-fertilising plants can migrate, and 

 "so obtain new peculiarities from fresh surrounding 

 " media, then they may acquire astonishing vigour, 

 " and even oust the native vegetation of the country 

 "they have invaded." According to this view the 

 male and female sexual elements must become in such 

 cases differentiated through the action of the new 



* Mr. Henslow has published passages in this book, and en- 



an elaborate review of the present deavoured to make others clearer, 



work in the ' Gardeners' Chroni- owing to Mr. Henslow's criticisms, 



cle ' from Jan. 13th to May 5th, but I can by no means agree with 



1877, also in ' Science and Art,' many of his inferences. I have 



Muy 1st, 1877, p. 77 ; from which also profited by an able review by 



latter jourial the quotation is Hermann Mtiller in 'Kosmoe,' 



taken. I have modified some April 1877, p. 57. 



