308 SIZE OF THE COROLLA. Chap. VII. 



metamorphosed stamens. That the lessened size of the 

 corolla in the above case is in some manner an indirect 

 result of the modification of the reproductive organs is 

 supported by the fact that in Rhamnus catharticus not 

 only the petals but the green and inconspicuous sepals 

 of the female have been reduced in size; and in the 

 strawberry the flowers are largest in the males, mid- 

 sized in the hermaphrodites, and smallest in the fe- 

 males. These latter cases, — the variabilitv in the size 

 of the corolla in some of the above species, for instance 

 in the common thyme, — together with the fact that it 

 never differs greatly in size in the two forms — make 

 me doubt much whether natural selection has come 

 into play ; — that is whether, in accordance with H. Miil- 

 ler's belief, the advantage derived from the pollenif erous 

 flowers being visited first by insects has been sufficient 

 to lead to a gradual reduction of the corolla of the fe- 

 male. We should bear in mind that as the hermaphro- 

 dite is the normal form, its corolla has probably retained 

 its original size.* An objection to the above view should 

 not be passed over; namely, that the abortion of the 

 stamens in the females ought to have added through the 

 law of compensation to the size of the corolla ; and this 

 perhaps would have occurred, had not the expenditure 

 saved by the abortion of the stamens been directed to the 

 female reproductive organs, so as to give to this form 

 increased fertility. 



* It does not appear to me that serves to protect their pollen from 



Kerner's view ( ' Die Schutzmittel rain. In the genus Thymus, for 



des Pollens,' 1873, p. 56) can be instance, the aborted anthers of 



accepted in the present cases, the female are much better pro- 



namely, that the larger corolla in tected than the perfect ones of the 



the hermaphrodites and males hermaphrodite. 



