REVIEW AND SUMMARY. 261 



REVIE"W AND SUMMARY.i 



After such exercises as those outlined in the preceding 

 pages, even if only a small number of families have been 

 studied, the student can hardly fail to have Degrees of 

 grasped the conception of degrees of relation- relationship, 

 ship, a conception that lies at the very foundation of bio- 

 logical science.^ If we now extend our study farther, and 

 compare families with each other, as we have been com- 

 paring their genera, we shall find that the principle is 

 general, and that families, as well as genera and species, 

 show relationships among themselves, falling naturally into 

 larger groups to which the term " order " is now commonly 

 applied.^ In some cases these groups are distinctly marked, 

 and the close relationship of the families composing them 

 is unmistakable, while in others the afQnities of a family 

 are obscure. In an inquiry of this kind there are neces- 

 sarily inherent difficulties, and it must be said frankly, that, 

 in the present state of botanical science, it is impossible to 

 construct a system that will fully and truthfully represent 

 the relationship of families of plants to each other. Never- 

 theless it is desirable before proceeding farther to notice 



1 It is assumed that the order recommended on page 96 has been fol- 

 lowed, or at least that the student has acquired a reasonably familiar 

 acquaintance with the prominent families of flowering plants. 



2 ' ' For myself, there comes from the eighth year memory of an 

 awakening to the conscious grasp and knowledge of genus and species. 

 I see it yet ... in my lap the shredded petals of almond, plum, and 

 the yellow rose of Persia, and in myself sense of a new concept and tool 

 for classifying and accumulating knowledge through all life." — Taloott 

 Williams, in the Century, January, 1893. 



8 "Natural order" is still employed by many writers as equivalent to 

 family, but the usage indicated above is becoming prevalent. 



