114 FERNS THE ANCESTORS OF FLOWERS 



The dispersal of the male-spores, or pollen, by wind 

 was the earlier method ; it was not until a late geological 

 period — the cretaceous, or chalk — that (as their fossil 

 remains show us) insects capable of feeding on -the honey 

 of flowers, and coloured flowers capable of attracting the 

 insects by sight, came into existence ; and it is since that 

 period that all the wonderful relations and adaptations of 

 flower to insect, and insect to flower, have been brought 

 about. V Before that, the wind-blown pollen-grains, or male- 

 prothallus-spores, were in such profusion that some of 

 them were carried by the wind to the surface of the car- 

 pellary leaflets of the female cones, or rosettes, as occurs 

 to-day in the pine-trees which shed enormous quantities 

 of pollen-dust in the spring. There the pollen spore 

 germinated instead of waiting to reach the ground and 

 produce its little thread-like prothallus. In early geological 

 times (Oolitic) — as we know from certain rare trees which 

 have persisted from those times, when they were very 

 abundant, to this day, viz. the Japanese Gingko tree, or 

 Maiden's Hair fern-tree, and the Cycads, or palm-conifers 

 — the little " prothallus " which emerged out of the pollen- 

 spore was not a simple filament as it is in the case of the 

 pollen of our modern flowering plants. The pollen-spore 

 of the Gingko tree and the Cycads actually produces in 

 these survivors of primitive forms at least one sperm-sac 

 containing liquid in which are motile sperms. And the 

 egg-pit of the female prothallus developed from the big 

 spores borne by the carpellary leaflets of the female 

 flowers is not so reduced or simple a thing as it is in 

 modern flowering plants. It is a real pit containing liquid, 

 and the motile sperms from the pollen's prothallus which 

 pushes itself into the little pit, are liberated and swim 

 about in the liquid of the reservoir or chamber formed by 

 the egg-pit, and then fuse with the egg-cells there em- 

 bedded and fertilise them. We see there is still a great 



