PREFACE. V 



This includes a rather careful study of representative examples 

 among the algae, fungi, liverworts, mosses, ferns and their 

 allies, gymnosperms and angiosperms, with especial emphasis 

 on the form of plant parts, and a comparison of them in the 

 different groups, with a comparative study of development, 

 reproduction, and fertilization, rounding out the work with a 

 study of life histories and noting progression and retrogression 

 of certain organs and phases in proceeding from the lower to the 

 higher plants. Thus, in the algae a first critical study is made 

 of four examples which illustrate in a marked way progressive 

 stages of the plant body, sexual organs, and reproduction. Addi- 

 tional examples are then studied for the purpose of acquiring a 

 knowledge of variations from these types and to give a broader 

 basis for the brief consideration of general relationships and 

 classification. 



A similar plan is followed in the other great groups. The 

 processes of fertilization and reproduction can be most easily 

 observed in the lower plants like the algae and fungi, and this 

 is an additional argument in favor of giving emphasis to these 

 forms of plant life as well as the advantage of proceeding logic- 

 ally from simpler to more complex forms. Having also learned 

 some of these plants in our study of physiology, we are following 

 another recognized rule of pedagogy, i.e., proceeding from 

 known objects to unknown structures and processes. Through 

 the study of the organs of reproduction of the lower plants and 

 by general comparative morphology we have come to an under- 

 standing of ths morphology of the parts of the flower, and of 

 the true sexual organs of the seed plants, and no student can 

 hope to properly interpret the significance of the flower, or the 

 sexual organs of the seed plants who neglects a careful study 

 of the general morphology of the lower plants. 



Part III. Plant members in relation to environment. This part 

 deals with the organization of the plant body as a whole in its 

 relation to environment, the organization of plant tissues with 

 a discussion of the principal tissues and a descriptive synopsis of 

 the same. This is followed by a complete study from a biological 



