A GREEN LEAF 75 



very small fraction of the weight of the dried 

 leaves remaining. 



Hence we conclude that fresh leaves consist of 

 water to the extent of about four-fifths of their 

 substance, while the remaining fraction is largely 

 carbon or charcoal, though they contain a small 

 percentage of mineral matter, probably averaging 

 from about two to seven per cent, of the whole. A 

 certain gaseous portion has also been burned away 

 into the atmosphere during the experiment, but 

 we need not consider this. 



This extremely small fraction, by weight, of 

 ash, is ne\'ertheless ver\' important to the plant, 

 and has been absorbed by the roots in solution, 

 from the soil. And this is practically all that 

 plants, generally speaking, obtain from the soil 

 except water. Where, then, did the plant obtain 

 its great weight of carbon from ? 



When we stand by a great (.)ak-tree and admire 

 its monstrous girth, and think of its many tons of 

 solid substance, chiefly built up of carbon obtained 

 from the air by the lea\'es during smiiight, year 

 after year, surely we must recognise that a leaf is 

 not the least significant of Nature's works. 



The wonderful arrangements ot cells that we 

 have examined in the leaf perform this great work 

 unceasingly, from the springtime, when they are 

 spread out in the newly born leaf, until its fall in 



