Co-OPERATION AND THE ORIGIN OF FLOWERS. 157 
tioned insects as a possible cause of variation, and the great 
Lamarck fully realised the effect of environment; all plants 
subject to these conditions (excessive sunshine, dry climate, 
and insect enemies) would vary in the same way. So long as 
they lived in this environment there would be no reversion. 
Such a variation is not a freak to be promptly swamped 
by crossing. It should not be called a ‘‘ mutation,’’ for this 
expression means an inexplicable miracle. 
The formation by De Vries of a five-leaved clover ex- 
plains how such a variation once formed could be rapidly 
improved and fixed. The ruthless shears of natural selection 
would keep all changes in the right direction, i.e , towards 
economy and efficiency 
Once true flowers were formed, they would surely 
develop rapidly. 
The Cretaceous was practically a new world with an 
increasing diversity of climates and of physical conditions. 
So the new type of piant and its insect clients would multiply 
and divide into orders, genera, and species until all habitable 
parts were occupied. 
Do we not see in the life of any plant, from the germina- 
tion of the seed until death, a continual adjustment to the 
ever-altering conditions of its environment Every action of 
the outside world must be countered by a fitting reaction of the 
plant itself, at least, if it is to survive. 
This side of Lamarck’s theory is surely obvious, and the 
rapid domination of true flowers in the chalk period is just 
what one should expect. 
Yet flowers did not develop until the earth was ready 
for them. The unspecialised adaptable plant found itself in 
a very evil state, suffering from the attacks of insects also 
still of a generalised type. 
The co-operation of new physical conditions, of a suit- 
able vegetable, and of appropriate insects, have resulted in 
the modern world of flowers. 
Nor was there any necessity (so far as we can tell) for 
these three independently evolved factors ever to have co- 
