PLANT ALCHEMY 273 



when it needs to be translocated. Sugar seems to be 

 the first product of the chemistry involved in carbon 

 assimilation by the leaf under the influence of light, 

 heat, and chlorophyll, and sugar is probably used by 

 protoplasts in the manufacture of starch. The soluble 

 sugar made in the leaves, in the first place, may probably 

 be commandeered for immediate use in the leaf and 

 elsewhere, while that in excess of immediate require- 

 ments may be converted into starch, and thus constitute 

 a reserve. Possibly when reserve starch is drawn upon 

 for nutriment its conversion into soluble sugar is accom- 

 plished by the agency of the ferment known as " dias- 

 tase." Human indebtedness to plants that build up a 

 starch reserve in cereal grains is beyond assessment. 

 Cellulose is the most important constituent of cell-walls, 

 and also occurs as a reserve substance, for instance, in 

 the Date-stone, in which the cell- walls are greatly 

 thickened and are dissolved in germination. 



In addition to the products already named, and that 

 may be considered as chief, there are others, due to 

 plant alchemy, all of value to the plants in which they 

 occur, and some of economic service to man. Among 

 these are ethereal oils, resins, caoutchouc, hydrocyanic 

 acid, tannin, malic, acetic, citric, and oxalic acids, and 

 various alkaloids, including strychnine, morphine, 

 caffeine, quinine, and cocaine. Indeed, the more com- 

 pletely we become acquainted with the organic com- 

 pounds elaborated by plants, the more astounded are 

 we at their variety and mystery. And in all our in- 

 quiries we cannot overlook the majesty and wonder of 

 living protoplasm, the most marvellous substance in 

 creation, which is capable of performing the most 



35 



