82 BOTANY. 



generally m the form of starch (e.g., the cerea. grainc), 

 and sometimes in the form of oily matters (e.g., the seeds 

 of mustard; flax, castor-bean, squash, etc.). 



160. The Use of Reserve Material. — In the use of reserve 

 material, as in the germination of starchy seeds, the starch 

 appears to undergo a change exactly like that in its disap- 

 pearance from chlorophyll. Here it is certain that oxygen 

 is absorbed, and that carbon dioxide is evolved, while the 

 starch is transformed into glucose. Similar transforma- 

 tions doubtless take place in the use of the starch stored 

 up in buds, twigs, stems, bulbs, etc. 



161. In the germination of oUy seeds, after the absorp- 

 tion of oxygen, starch is (in many cases, at least) first pro- 

 duced, and from this the soluble sugar is formed. In any 

 ease, after the solution is attained the subsequent changes 

 are similar to those which follow the transformation of the 

 starch of the chlorophyll. 



" 162. The Nutrition of Parasites and Saprophytes is simi- 

 lar to that of embryos, buds, bulbs, etc. Here assimilated 

 materials are drawn from some other organism, and subse- 

 quently undergo digestive 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 sapro- 

 phytes, while the remainder is elaborated by their chloro- 

 phyll. 



163. Many cultivated plants, as we grow them, are par- 

 tially saprophytic, deriving a portion of their nourishment 

 from decaying organic matter in the soil. The so-called 



