CHBMISTB7 AND PETSlCS OP PLAJHT8. 83 



carnivorous plants, as the sundews (Drosera), fly-trap 

 (Dionsea), pitcher-plants (Sarracenia), etc., are in reality 

 partially saprophytic, obtaining a considerable part of their 

 food-materials from decaying animal matter. 



164. For convenience the various processes which take 

 place in the digestion of starch, the storing of reserve ma- 

 terial, the use of other food-matters, etc., have all been in- 

 cluded under one general term — Metastasis, or Metabolism. 

 It has been made to include all chemical changes in the 

 plant excepting assimilation (starch-making). Assimilation 

 and metastasis thus include all chemical changes taking 

 place in green plants. In all plants there is metastasis, 

 while assimilation is present in those only which contain 

 chlorophyll. 



165. Alkaloids and Acids. — Among the most obscure of 

 the metastatic changes are those which give rise to the 

 alkaloids. These are compounds of carbon, hydrogen, ni- 

 trogen, and generally oxygen, as follows: 



Nicotine (CioHmNs), found in tobacco. 

 Cinchonia (CS0H24N2O), found in Peruvian bark. 



Morphia (CnHigNOa + HjO), found in the opium-poppy. 

 Strychnia (CjiHaaNaOg), found in the seeds of Strychnos. 



Caffeine (0$ H10N4OJ-I- HjO), found in coffee and tea. 



166. These and many others occur in plants in combina- 

 tion with organic acids, such as malic acid (C^HjOJ ; tartaric 

 acid (C,H„0,); citric acid (C„H,0,); oxalic acid (C,H,0,); 

 tannic acid (C^H.^O,,); quinic acid (C,H„0„); meconic 

 acid (C,H,0,). These acids are probably formed by the 

 oxidation of some of the sugary or starchy substances in 

 the plant, while the alkaloids with which they are combined 

 appear to have some relation to the nitrogenous constitu- 

 ents of the protoplasm. 



