The Effect of Cross-Fertilization on Incon- 
spicuous Flowers. 
BY 
ANNA BATESON, 
Nezvnham College , Cambridge. 
I N discussing the relation of the conspicuousness of flowers 
and the advantages of cross-fertilization, Darwin comes to 
the conclusion that small inconspicuous flowers, which are not 
visited by insects as a rule, and which are perfectly self-fertile, 
must probably still be capable of benefitting by an occasional 
cross, for if they could not benefit in this way their flowers 
would gradually have become cleistogene. ‘ As therefore no 
species which at one time bore small and inconspicuous 
flowers has had all its flowers rendered cleistogene, I must 
believe that plants now bearing small and inconspicuous 
flowers profit by their still remaining open, so as to be 
occasionally intercrossed by insects. It has been one of the 
greatest oversights in my work that I did not experimentise 
on such flowers, owing to the difficulty of fertilising them, and 
to my not having seen the importance of the subject 1 / The 
following experiments were undertaken in the hope of deciding 
this question. The plants experimented on were Senecio 
vulgaris , Capsella Bursa-pastor is , and Stellar ia media. 
I. — Senecio vulgaris. 
With regard to this plant, H. Muller says that the nectar is 
easily accessible in the tubular florets, but the absence of 
ray-florets and the small diameter of the capitula render 
them very inconspicuous, and he never saw them visited by 
insects 2 . This plant is perfectly adapted for self-fertilization, 
1 Darwin, Cross and Self-Fertilization of Plants, p. 387. 
2 H. Muller, Befruchtung der Blumen, p. 399. 
[Annals of Botany, Vol. I. Nos. Ill and IV. February 1888.] 
