EFFECT OF DIFFERENT LIGHT INTENSITIES ON PLANTS. 



19 



At the end of the experiment no consistent effect could be noted 

 which could be ascribed to the use of the fan. The best growth was 

 found between n/5 and n/2 light, a marked decrease being noticeable 

 in full light. In the shades no great reduction in growth occurred 

 until the light was reduced to n/15, and even at the end of the experi- 

 ment plants were alive and in good condition in n/93, although they 

 had produced no leaves aside from the cotyledons. Cotton, therefore, 

 showed more tolerance of shade than any of the other plants used in 

 these experiments. 



CORX. 



Corn showed considerably more tolerance of shade during the early 

 portion of the experiment than either mustard, lettuce, or radish. 



Fig. 10.— Relative sizes of cotton plants 50 days after germination. The numbers correspond to those of 

 the shades and the letters indicate the two beds in the experiment. (Traced from photograph.) 



probably as a result of the larger seed and consequent greater food 

 supply. At the end of 30 days plants were still living in n 93 light, 

 and in bed A plants remained alive in n/15 until the end of the experi- 

 ment, or 50 days. On the whole, however, the best plants were pro- 

 duced in the strongest light (Table VII), and in this respect the results 

 with corn differ from those with cotton, potato, radish, lettuce, and 

 mustard. While the plants were tallest in n/7 to n/2 light, the stems 

 had the greatest diameter in the strongest light. The most interesting 

 fact brought out in the case of com was that although the plants grew 

 fairly well with as slight illumination as n/15, and although with a 

 light intensity of n/93 plants maintained themselves in the bed with 

 the fan for 30 days, all plants had disappeared from the portion of the 

 beds receiving this intensity of light before the end of the experiment, 

 and in the bed without the fan they had also disappeared in n 1 5 light. 



279 



