CHAPTER VIII 

 FERNS THE ANCESTORS OF FLOWERS 



WE have seen that the spores of ferns falling on the 

 ground produce little flat green patches the "pro- 

 thalli " upon which female egg-pits and male sperm-sacs in 

 due course make their appearance, and that the microscopic 

 screw-like sperms (or " antherozoids " as the botanists call 

 them) escape from the sacs and actively swim to the egg- 

 pits through the film of water covering the damp growth. 

 They enter the egg-pits and " fertilise " the contained 

 egg-cell. All plants simpler than ferns, such as horse- 

 tails, mosses, seaweeds, and water-weeds (with some excep- 

 tions) have actively motile aquatic " sperms " like those of 

 the ferYi. And so, be it noted, have animals. All plants 

 higher and more elaborate than the ferns such as the 

 conifers and flower-bearing trees, shrubs, and herbs (with 

 the rare exception among living plants of the Gingko 

 tree and the Cycads), cease to produce aquatic motile 

 sperms. Their male spores are the familiar dust-like dry 

 " pollen " from which, when it falls on the sticky stigma 

 of the flower a solid filament grows and penetrates to 

 the egg-cells buried in the germen, or egg-holding central 

 part of the flower. Thus, ferns seem to represent a 

 stage half-way between the lower plants and the higher. 

 And as a matter of fact, in regard to many points of 

 their structure, they do. Recent discoveries of fossil fern-like 

 plants of great age have led to the definite conclusion that 





