162 SYMBIOSIS 



part of the plant what a difference this would have made to his 

 account of the evolutionary process. 



On another page he tells us again, as he thinks, in evidence 

 of " The Struggle for Existence " that 



Flowers have been specially adapted to the kinds of insects that most 

 abound where they grow. 



He instances amongst others the gentians of the lowlands as 

 being " adapted " to bees ; those of the high alps being " adapted " 

 only to butterflies. 



From the point of view of Bio-Economics, however, this state- 

 ment is very incomplete. It leaves out some essential points 

 and slurs over the fact that we have here examples of the mutual 

 accomodation of beings according to qualification and mutual 

 worth. A little reflection will show that it is in the first place the 

 bio-economic usefulness of the plant which renders possible 

 the systematic biological traffic here concerned ; and, further, 

 that it is the quality of the insects' service which determines 

 their success in obtaining the boon and the far-reaching good 

 effects of this desirable biological trade. More particularly, as 

 was abundantly shown in the preceding pages, and must on no 

 account be omitted in this connection, the pre-requisites of 

 successful biological trade are these : cross-feeding and mutual 

 forbearance. It should be expressly mentioned that the vast 

 numbers of insects which fail as regards the aforesaid pre- 

 requisites are ipso facto excluded. They do not " come in " 

 at all. Having failed to qualify for high symbiotic service, they 

 have no legitimate claim to the biological remuneration incidental 

 upon such service. That the Symbiosis between flower and 

 insect is often marked by highly specialised " adaptations " 

 which have an interest of their own for the mere morphologist 

 has its reason in special contingencies, which we are not wrong 

 in interpreting as bio-economic contingencies. Flowers adapted 

 to be fertilised by one class of insects, as, for example, by bees, 

 in Wallace's own words, stand in danger of having their nectar 

 extracted by another class, e.g., by flies, without effecting cross- 

 fertilisation. The would-be robbers, therefore, have to be foiled ; 

 and flowers have from time to time to be modified in structure 

 according to such (bio-economic) contingencies. We know that 

 modifications thus interpretable frequently occur. Such modifica- 

 tions in effect amount to this : the flower dedicates, gives, or 

 " adapts " itself to those animals which qualify most in Symbiosis. 



