116 THE BIOLOGY CF A PLANT. 



7. EMBEYOLOGY 



Except in its general features, this is too difficult for the be- 

 ginner. He may, however, observe the later stages by studying 

 old prothallia with the young fern just appearing, and young 

 ferns with the prothallia still adherent. 



G. Chlorophyll and Starch. 



Vigorous prothallia aiford excellent examples of cells bearing 

 chlorophyll-bodies in which starch is easily detected. 



1. Study some of the marginal cells with your highest power, 

 paying special attention to the chlorophyll-bodies and their ar- 

 rangement. 



2. In favorable cases observe the opaque rod-like or oval 

 starch grains inside them. 



3. Prove by reagents that these are starch grains. 



