Show chlorophyll as essential to flower foliage as Is blood to human beings it is generally understood that growing plants require light but few gardeners know the effect that certain colored rays have upon green stems and leaves dr earl S johnston of the smithsonian in situation sit ution in washington has carried out some interesting experiments with colored light to discover what hue is the most favorable for grow ing plants sunlight is necessary for the for mation of chlorophyll chlorophyll is as essential to flower foliage as is blood to human beings it is the substance that gives the plant its green color without it lea leaves es turn brown wither and die doctor johnston has discovered that chlor ophell is formed better under red light than blue sunlight we e knob is made up of many colored rays the plant seems to pick out th tl e col ored ray it needs for substance plants require blue rays as ell as red in order to produce starch and sugar both red and blue rays are necessary to absorb carbon di oxide which is part of the process involved in the manufacture of I 1 starch doctor johnston has made a rotating wheel which varies the hues he ile has found that as the mixtures of color rays closely meet the combination of rays in pure sunlight the plants grow normally while on the other hand plants appear to grow abnormally if any particular hue is accented the shapes heights and types of plants in one part of the world seem to differ from those in another locality this seems to prove that the sunlight in the polar regions is unlike that in tropical places |