ON GUM AND SUGAR TREES 



plasm itself and they differ from the gum and 

 resins that we have just been considering in that 

 each molecule contains at least one atom of 

 nitrogen. 



The sugars, it will be recalled, occupy an inter- 

 mediate place, inasmuch as they, unlike the resins 

 and rubber, contain oxygen; but they contain no 

 nitrogen. The formulae given by the chemist for 

 the different alkaloids are intricate but they differ 

 from one another only in the matter of a few more 

 or a few less atoms of one or another of the four 

 constituents of 1 which they are all made up. 



There is, for example, only the difference of 

 one atom of carbon and of four atoms of hydrogen 

 between a molecule of quinine and a molecule of 

 strychnine. Considering that the molecules com- 

 prise in the aggregate not far from fifty atoms, in 

 each case, this discrepancy seems trifling. That 

 the two drugs should have such utterly different 

 effects upon the human system is a mystery that 

 will be solved only when a much fuller knowledge 

 is gained as to the physiological processes than 

 anyone has at present. 



But the plant developer, of course, has no con- 

 cern with this aspect of the subject. What inter- 

 ests him is the knowledge that different races of 

 cinchona trees, for example, are known to vary 

 greatly as to the proportion of commercial alka- 



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