DOMAIN OF EVOLUTIONARY HYPOTHESIS 125 



Two sorts of spores occur microspores which form 

 prothalli with seed-vessels, antheridia, and macrospores 

 which produce such with embryo ova (archegonia). 



Four classes of this series are determined : Ferns 

 (Filicinae), Equisetums (Equisetae), Lycopods (Club- 

 mosses), Water Ferns (Hydropteridse). 



4. Gymnospermae or Naked-seeded Plants. Woody 

 plants with separated male and female flowers. In 

 the stamens are produced multicellular pollen grains 

 which are carried by the wind direct to the more or 

 less obvious (naked-seeded) female embryo seeds. 

 Several embryo ova are found in the embryo seed. 



The first classes of this series are : Cycadinao 

 (Sago or Fern Palms), Ginkgoinae (a still living species 

 is GinJcgo biloba), Coniferae (Fir Trees), Gnetinae (a 

 small exotic group). 



5. Angiospermse or plants with covered seeds. 

 The flowers often contain both male and female organs 

 at the same time ; more rarely these are borne in 

 separate flowers or even separate plants. The pollen 

 grains are only two-celled ; fertilization can only occur 

 when the pollen grains, on germination on the stigmatic 

 surface, send a tube down through the entire stalk till 

 it reaches the entirely enclosed embryo ova in the seed 

 vessel. Each embryo only contains one ovum. 



The chief divisions are : Monocotyles and Dicotyles. 

 The series 4 and 5 are distinguished from the other 

 three as flowering or seed-bearing plants. A flower 

 is produced at the terminal point of a shoot and con- 

 sists exclusively of reproductive organs. The leaf 



