6 THE PLANT WORLD. 



TABLE in. 

 Period ending. Sunshine. Shade. Ratio. 



June 17 105 28 3.75 



June 24 80 20 4.00 



July I 84 57* 1-50 



July 8 127 50 2.5 



July 15 77 26 3.0 



July 22 ^S 40 1.7 



July 30 66 50 1.3 



August 6 34 20 1.7 



August 12 33 37 -9 



August 19 20 39 .5 



August 26 36 44 .82 



September 2 



September 9 102 55 1.9 



September 16 137 57 2.4 



September 23 175 50 3.5 



October 2 158 46 3.4 



October 9 105 25 4.2 



The gradual decrease in the weekly rate during the 

 months of July and August was at least in large part due to 

 growth of the strawberry plants about the instrument, practi- 

 cally covering the cup. These were cut away August 26, 

 after which the rate suddenly increased remarkably. This 

 emphasizes the shade influence of one plant upon the condi- 

 tions for the growth of others. 



At the time of the removal of the strawberry vines sur- 

 rounding the instrument in the open, some green algae were 

 discovered on the cups, which were therefore both removed 

 to a laboratory room and operated for one week under ex- 

 actly the same conditions. Both lost the same amount of 

 water during that period. In this case one cup had evapo- 

 rated 41 1 cc, while the other had lost 728 cc, and yet there 



♦The comparatively high rate for this week was at least partly due 

 to an Injury to the tent which exposed the instrument for forty-eight hours. 



