140 CO-OPERATION AND THE ORIGIN OF IF'LOWERS. 
plants were in existence. During this last period they be- 
came dominant and spread all over the earth as then habitable. 
As to the place where, there is really no evidence at all. In 
Portugal and the United States remarkable discoveries have 
been made, but that does not really give any satisfactory 
basis for speculation as to the original birthplace. 
The most important question, however, is in what sort 
of climate did the first of all flowers unfold its petals? 
During the Jurassic era, which preceded Neocomian 
times, equable, warm, wet, temperate conditions seem to have 
extended very far North and also to the extreme South. 
Cycadlike plants and various Gymnosperms, as well as Ferns 
and Fernlike plants, were abundant, and give an impression 
of a mild, moist climate in which vegetation was luxuriant. 
It seems, in the first place, unlikely that a completely 
new type of plant would have any chance of developing amidst 
rapid-growing ferns, Cycads and the like. One has to remem- 
ber that an evolution of the crust of the earth has been steadilv 
proceeding through all the geological ages. The surface has 
been thrown into folds, thrust up into mountains, and let 
down into rifts and deep sea abysses. 
Accompanying this evolution and the consequent changes 
in rainfall, in wind directions, in sea currents, in the 
accumulation of snow fields, etc., there has been a slow de- 
velopment, ending in the almost infinite variety of the world’s 
climates to-day. 
One cannot possibly assume such diversity of conditions 
in the Jurassic period. Yet there may have been even then 
ridges or hills of no great altitude which were exposed to 
strong sunshine and drying winds. 
As a working hypothesis let us suppose that a climate of 
this nature, similar to that of Palestine or the Riviera, did 
exist in the Jurassic period or possibly at a still earlier date. 
Our original Cycadlike ancestor was endeavouring to 
grow there, and would undoubtedly find that these conditions 
were novel and uncomfortable. 
Its sporeleaves may have resembled the male sporeleaves 
of Bennettites or of certain Cycadlike fossils. The sporangia 
