No. 508] STUDY OF VASCULAR ANATOMY 



22\) 



When this type of work was introduced into the labora- 

 tories of this country, almost any available material was 

 used. This material was studied in great detail, impor- 

 tant and trivial things being kept at a dead level. The 

 purpose was to train in observation rather than to develop 

 any picture of the plant kingdom. This detailed study 

 meant the handling of a few types. The pedagogical 

 slogan of those days was a few types thoroughly studied. 

 The few types selected were naturally those most avail- 

 able, and by some irony of fate these most available things 

 turned out to be the most unrepresentative types possible. 

 You are familiar with the old list: Spirogyra, standing 

 for green alga; Marchantia, for liverworts; a leptospo- 

 rangiate fern, for pteridophytes, and so on. Now all this 

 has been changed. The purpose is to give some concep- 

 tion of the evolution of the plant kingdom, not in detail 

 or in any rigid way, but in general perspective. The 

 threads on which the facts are strung are such as these : 

 the transition from a one-celled to a many-celled body, 

 the evolution of reproductive methods, the origin and 

 differentiation of sex, the acquisition of the land habit, 

 the origin and development of the alternation of genera- 

 tions, the origin of the leafy sporophyte, the evolution of 

 the vascular system, the evolution of the seed, the origin 

 and evolution of the flower. How can " a few types thor- 

 oughly studied" illustrate such things or give any such 

 perspective ? 



This means much illustrative material, carefully 

 selected, and each form used to illustrate some definite 

 and important fact. It is not many types hastily studied, 

 but many types studied carefully for the few points that 

 are really important. The difference between the older 

 view and the recent one, both in teaching and in research, 

 is the difference between an indiscriminate mass of un- 

 related Details obtained from a few representative forms, 

 and a selected mass of related details obtained from a 

 large number of representative forms. 



These somewhat miscellaneous statements may serve 



