- 88 - PHOTOSYNTHESIS. 



29. Formation of starch around pyrenoids of Spirogyra chloroplasts in the 



light. Filaments fixed and stained with iodine after having been (a) exposed to 

 daylight, and (6) kept in darkness. 



30. The absorption-spectrum of chlorophyll. 



31. Demonstration showing which light rays are effective in photosynthesis. 



Rapid bubbling of oxygen from an aquatic plant in white light slowed by interposing 

 an orange glass and nearly stopped by a green glass. Examine the absor^ tion-spectra 

 of the orange and green glasses. 



32. Red photosynthetic pigment in marine algae. 



