182 BOTANY. 



similar to those which follow the transformation of the 

 starch of the chlorophyll. 



238. The Nutrition of Parasites and Saprophytes is 

 similar to that of embryos, buds, bulbs, etc. Here assimi- 

 lated materials are drawn from some other organism, and 

 subsequently undergo metastatic changes. In some cases the 

 parasitism is only partial, as in the mistletoe, where a part 

 of the assimilated matter is formed in the parasite (which, 

 therefore, contains chlorophyll), while a portion seems to be 

 taken along with the mineral salts from the host plant. So, 

 too, there are plants which are partially saprophytic in habit, 

 deriving a part of their nourishment as saprophytes, while 

 the remainder is elaborated by their chlorophyll. Many cul- 

 tivated plants, as we grow them, are partially saprophytic, 

 deriving a portion of their nourishment from decaying or- 

 ganic matter in the soil. The so-called Carnivorous plants, 

 as Drosera, Dionaea, Sarracenia, Darlingtonia, Nepenthes, 

 TJtricularia, etc., are in reality partially saprophytic, obtain- 

 ing a considerable part of their food materials from de- 

 caying animal matter. 



239. The Formation of Alkaloids. Among the most 

 obscure of the metastatic changes are those which give rise 

 to the alkaloids. These are compounds of carbon, hydro- 

 gen, nitrogen, and generally oxygen, in which the first two 

 elements have approximately an equal number of atoms, 

 while the last two have also a nearly equal but much smaller 

 number. 



The more important ones are the following : 



Conia (C 8 Hi 8 N,) from Conium. 

 Nicotine (Ci Hi 4 N 2 ) from Tobacco. 

 Cinchonia (C 20 H 24 N 2 O) from Peruvian Bark. 



Morphia (Ci 7 H 19 NO S + H 2 O) from the Opium Poppy. 

 Strychnia (C 2 i H 22 N 2 O 2 ) from the seeds of Strychnos. 

 Caffeine (C 8 H, N 4 O 2 + H a O) from Coffee and Tea. 



These and many others occur in plants in combination 

 with organic acids, such as : malic acid (C 4 H 6 6 ) ; tartaric 

 acid (C 4 H 6 6 ) ; citric acid (C. H 8 7 ) ; oxalic acid (0, H 

 4 ); tannic acid (C M H M IT ) ; quinic acid (C, H 14 0.) ; 

 meconic acid (C, H 4 0.). These acids are probably formed 



