160 
POPULAR SCIENCE REVIEW. 
THE FERTILISATION OF VARIOUS FLOWERS BY 
INSECTS. (COMPOSITE, ERICACEAE, &c.) 
BY WILLIAM OGLE, M.D., F.R.C.P. 
[PLATE LIX.] 
A VERY short time ago it was considered a sufficient ex- 
planation of the various colours and forms of flowers to 
say that they were devised to please the eye of man by their 
brilliancy and their variety. This no longer satisfies us. For 
we have learnt from Mr. Darwin, that every detail of structure 
in an organism exists purely and solely for the sake of that 
organism itself, or because it was of use to the ancestors of the 
organism, and has been derived from them by inheritance. If 
anyone bear this general law in mind, and examine by its light 
a number of different flowers, he will, I think, be led inevitably 
to two conclusions. Firstly, he will be convinced that the 
purport of a nectary is to attract insects, and that those flowers 
which possess one require the visits of insects for their due 
fertilisation. A second conclusion will be this : That any 
notable irregularity of the corolla is also — if not invariably, yet 
usually — connected with the visits of insects, and has, like the 
nectary, for its ultimate object fertilisation by their agency. 
The manner in which the irregularity acts is not always the 
same. One very common result of it is to compel the insect to 
visit the nectary in some particular direction by barring up all 
others, that particular direction being such that the insect is 
made to impinge in a useful way upon stigma or upon anthers, 
as the case may be. Another very frequent purport of the 
irregularity is to compel the insect to alight on a particular 
part, where its weight causes certain mechanical effects by 
which the pollen is transferred to the body of the insect and is 
then carried off to the stigma, perhaps sometimes of the same, 
but more frequently of some other, blossom. 
This view of the purport of irregularity throws light on a fact 
noticed in manuals of botany, but hitherto, so far as I know, un- 
