Environment and Adaptation 215 



nish the materials for the first stages of germina- 

 tion. In the higher plants the seeds contain similar 

 stores of food, either in the endosperm or less com- 

 monly in the outer seed-tissues, or in the tissues of 

 the embryo itself. Other types of storage organs 

 are bulbs, tubers, root-stocks, etc. 



PARASITES AND SAPROPHYTES 



The great group of fungi are all either para- 

 sites or saprophytes, and among the flowering 

 plants there are also found many species which 

 have become more or less completely parasitic 

 or saprophytic, but the latter are probably 

 all derived from forms originally possessing chloro- 

 phyll. Parasites and saprophytes are not common 

 among the archegoniates, but there are a num- 

 ber of examples known. Where plants are com- 

 pletely parasitic or saprophytic there is a com- 

 plete loss of chlorophyll, and with it a more or less 

 extensive degeneration of the leaves. The humus 

 saprophytes may also have their roots replaced by 

 root-like stems. These differences are evidently cor- 

 related with the marked changes in the method of 

 nutrition. 



Parasitic Flowering Plants. The normal green 

 plant derives most of its food from the inorganic 

 substances CO 2 and water, together with certain 

 nitrogenous and other elements absorbed from the 

 soil. There are, however, many plants which are 



