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, Dionsea, Sarracenia, Darlingtonia, Nepenthes, 

 Utricularia, 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 (Cs H15N,) from Conium. 

 Nicotine (Cio HiiNj) from Tobacco. 

 Cinchonia (C20 H24 Ns 0) from Peruvian Bark. 



Morphia (Ci, H19 N O3 -h H2 0) from the Opium Poppy. 

 Strychnia (Cji H22 Nj O2) from tlie seeds of Strychnos. 

 Caffeine (Cb Hjo N, O2 4- Ha 0) from Coffee and Tea. 



These and many others occur in plants in combination 

 with organic acids, such as : malic acid (0, H„ 0,) ; tartaric 

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

 0,); tannic acid (C„,H,^0„); q-wnic acid (0, H„ OJ ; 

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



