THE STAGE SETTING 



i:i 



a different wave length. In addition there is the non-visible radiant 

 energy of the ultra-spectrum. These different wave lengths ha\c 

 various effects on plants and animals. Chlorophyll, the gnnMi color- 

 ing matter of plants, which depends on the presence of light, absorbs 

 light waves only from the red and blue bands of the spectrum. 

 Whereas most of the radiant energy absorbed by a plant changes 

 to heat, a very small part of it, estimated at not more than 0.5 per 

 cent to 3 per cent, is used by the chlorophyll in the process of starch 

 making. As in the case of temperature, optimum light is necessary 

 for the best work of plants, some preferring shade and others living 

 at their best in bright sunlight. 



Light causes movements in leaves and stems as well as changes 

 in the size and shape of these organs. Plants respond to light, tlie 

 leaves being placed so as to get the most light possible. The amount 

 of light largely determines the shape of the entire plant, trees in a thick 

 forest having a very different shape from similar trees in the open. 



The length of daylight has an effect on plants. Some plants, like 

 the radish, spinach, and clover, require a long day to produce flowers 

 and fruit, while fall flowers, such as cosmos, dahlia, and ragweed, 

 require a short day in order to form flowers and fruit. It has been 

 shown experimentally that for each species there appears to be a 

 most favorable length of day for flowering, fruiting, tuber formation, 

 and other food-storing activities. This discovery is of great value to 

 agriculturists. 



60 



50 



40 



30 V 



20 



10 



Legend 



Diaptomus Lake Eaton 



Holopfdium 8<Q Sirnon Pond 



Cladocera LaVe Madeleine 



Diaptomus 



13 Noon 2 



10 



12 



6 8 10 13 Noon 



.V. Y. State Conscrralion Drpt. 



Curves showing the variation in nmnbers over a period of 21 hours of scvcriil 

 species of plankton organisms from three Adirondack lakes. W hiil factors might 

 be expected to influence their dislribiilion? 



