INTRODUCTION. 5 



delicate adjustments to care for that it is really impossi- 

 ble, as yet, for us to explain why all of its parts are placed 

 just as they are. In the beginning of the study of plants, 

 only some of the most prominent functions and life-rela- 

 tions can be considered. In order to do this, it seems bet- 

 ter to begin with single organs, and afterwards these can 

 be put together in the construction of the whole plant. 



