INTRODUCTION. 2CjI 



of the water, also possess xerophytic structures for the purpose 



of checking transpiration. 



Studies of Plants in their Relation to Animals. 



Studies in cross-pollination by the aid of insects would come 

 under this head. 

 Studies in Pollination brought about in other ways. 

 Studies of Nutrition as shown in parasitic plants, in sym- 

 biosis, etc. (See Chapter XV. ) 

 Studies in the Relation of Life Histories of plants to sea- 

 sonal changes as suggested in Chapter XXXVIII. Com- 

 pare in this respect plants which flower at different seasons of 

 the year. 

 Studies in the Struggle between Plants for the occupation 



of the land. (See Chapter XLVIII. ) 

 Studies in Soil Formation by plants. (See Chapter L.) 

 Studies in Zonal Distribution of plants and in plant com- 

 munities. (See Chapter XLIX. ) 

 Studies in the Relation of Plants to Climate. (See 

 Chapter LII. ) 



456. Suggestions. — Brief discussions of a few of these topics 

 are given here to suggest how such studies may be carried on- 

 with young pupils. For a fuller discussion of the topics 

 enumerated above, the student is referred to the author's larger 

 ' ' Elementary Botany ' ' and to the works dealing more largely 

 with the subject of ecology cited in the Appendix. But it 

 should be borne in mind that the beginning student cannot in 

 a few excursions make any systematic ecological study, since 

 some special knowledge of botany would be necessary as a 

 foundation. Some of the general truths, however, can be 

 observed. 



