igoo-i.] Effects of Water on Foliage Leaves. 325 



condition, while the others mentioned are produced by fungi or by 

 enzymes. 



This naturally leads up to the producing of the spotted leaf by 

 artificial means. There are various methods employed by the small, 

 but not too scrupulous tobacco dealers to produce an imitation of the 

 Sumatra leaf, as has been already mentioned, but these will not be 

 dealt with here as they have, so far as the writer can learn, no scientific 

 bearing upon the subject under discussion. There is a method, 

 however, of producing a spotted leaf by means of strongly alkaline 

 substances, applied with a sprayer to the leaves, a few days before 

 they are harvested. This process has been investigated in some detail 

 by the writer, and it is found that certain effects are produced upon 

 the leaves, which render them more desirable as a cigar wrapper, for 

 two reasons: — (i) They burn more rapidly and are less liable to 

 become extinguished than similar leaves not so treated. (2) The leaf 

 when cured has a more silky appearance, and is slightly thinner. As 

 to this latter it should be mentioned that a very limited number of 

 leaves were compared, and so too much stress should not be placed 

 upon it. With regard to the former it is found, by experiment with 

 different kinds of leaves, that when saturated with caustic potash, 

 caustic soda or carbonate of soda, then dried and ignited, they will 

 burn more evenly and readily than leaves not so treated. It is the 

 same, but to a much more noticeable degree, with filter paper, writing 

 paper and other kinds of paper. Leaves vary much in the capability of 

 being affected in this way, probably due to differences in chemical 

 constituents of the substances contained in the different plants. Both 

 paper and leaves, when not saturated with the alkali, have a tendency, 

 more or less marked, to burst into flame when ignited; while if first 

 treated, and then dried and ignited, they burn and glow steadily 

 without producing flame. 



The next question that naturally arises, is : — Do plants when 

 growing absorb through their leaves any of the alkali which is applied 

 to the leaf surfaces ? Certain experiments with the object of 

 answering this question, were performed at the Botanic Gardens, and 

 elsewhere, July, August and September (1899), in order to ascertain 

 whether leaves did absorb substances and transport them to other 

 parts of the plant. Species of the following genera were operated 

 on : — Solanum, Nicotiana, Aralia, Ampelopsis, Fraxinus, Pelargonium 

 and Helenium. The following solutions were used : — Caustic soda in 

 strengths of i, 2^^, 5, 10, 20 per cent. ; and sodium carbonate in 

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