Bui. 81, Bureau of Plant Industry, U. S. Dept. of Agriculture. 



Plate I. 



FIG.I.- LOWER ORGANISM. 



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F1G.2. HIGHER FUNGUS. 



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FIG.3.-MOSS. 



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FIG.4.-FERN. 



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FIG. 5-FLOWERING PLANT. 



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F1G.6.-HIGHER ANIMAL. 



Diagram Illustrating the Network of Descent, Succession of Generations, 



Alternating Phases, and Expansion of the Fertilized Egg. 



