PART IV. 
GENERAL RETROSPECT. 
In this section I propose to review the various structural 
features of flowers that have already been described in detail, and 
to trace their general effect on the life of the plant. If we cannot 
discover the causes, we may determine accurately the effects, of any 
modification in structure of a flower. 
The various characters of entomophilous flowers which affect 
the life of the plant may be grouped as follows :— 
1. Characters which influence the visits of insects— 
a, General attractions for anthophilous insects. 
-a. Colour or scent. 
8. Honey, pollen, shelter, or other substantial benefit. 
b. Increased attractions for certain insects, gained by the 
exclusion of others. 
a. By colour or scent. 
8. By concealment of the honey or pollen. 
y. By the time of flowering or the place of growth. 
2. Characters which influence fertilisation— 
a. Mutual adaptations of pollen and stigma. 
b. The insuring of cross-fertilisation in case of insect- 
visits, and of self-fertilisation in absence of insects. 
1.—a. CHARACTERS INDUCING INSECTS’ VISITS. 
a. Effect of Conspicuousness and of Odour, 
In the third section of this book, I have discussed so many 
cases of closely allied flowers differing in conspicuousness, and 
at the same time in abundance of insect-visits and in the chances 
