THE DUALITY OF INHEEITANCE 



in the reduced condition, N, and these germi- 

 nate into tlie prothallus, which accordingly is 



Fig. 7. — The prothallus of a fern, which reproduces by sexual 

 cells, eggs and sperm. The eggs are borne in the sac-like 

 "archegonia," just below the notch in the figure. They, 

 like the sperm-forming "antheridia," lie on the under sur- 

 face of the flattened prothallus which is here viewed from 

 below. Notice the root-hairs or rhizoids by which the 

 plant feeds. Highly magnified. (After Coulter, Barnes, 

 and Cowles.) 



N throughout. But when the prothallus forms 

 reproductive cells, no reduction occurs. Its 

 egg-cells and its sperm-cells in common with 



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