SLEMEiNTS OF STKUCTURAL BOTANY. 109 



CHAPTER XYI. 



CLASSIFICATION OF PLANTS ACCORDING TO THE NATURAL 



SYSTEM. 



177. Hitherto, our examination of jilants lias been 

 confined to a few selectetl specimens, and we have 

 examined these chiefly in order to become acquainted 

 with some variations in the details of growth, as exem- 

 plified by them. Thus, we have found plants whicli 

 agree in exhibiting two cotyledons in the embryo, and 

 others, again, which are monocotyledonous. Some 

 members of the former group were found to exhibit 

 two sets of floral envelopes, other only one, and 

 others, again, were entirely without these organs. And 

 so on through the various details. We now set out 

 with the vegetable world before us — a world populated 

 by forms almost infinite in number and variety. If, 

 therefore, our study of these forms is to be carried on to 

 advantage, we shall have to resolve upon some definite 

 plan or system upon which to proceed ; otherwise we 

 shall merely dissipate our energies, and our results will 

 be without meaning. Just as, in our study of language, 

 we find it convenient to classify words into what we 

 call pavts of speech, and to divide and subdivide these 

 again, in order to draw finer distinctions, so, in our 

 study of plants, it will be necessary to arrange them 



