IN TROD UC T20N. 29 1 



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 XL VIII. ) 

 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 LI I.) 



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. 



