4 Flowers and their Unbidden Guests. 



patiently provide ourselves with fresh building-stones 

 which shall be beyond suspicion. For the solution of 

 the questions at issue, experiments and observations 

 must be carried out with definite aim, so that all sub- 

 jectivity may be as far as possible excluded, and so 

 that each person may have it in his power to test their 

 accuracy by repetition. 



As regards one of the questions mentioned above as 

 underlying the theory of natural selection, namely, " the 

 primary cause of individual varieties or sub-species," 

 I shall have an opportunity this year in another place 

 of publishing a series of observations bearing on the 

 question. To the solution of the second question, 

 namely, " how far certain characters in the bearer are 

 of advantage to the same," the following pages may 

 furnish a small contribution. 



