148 VICTOR E. -HKLFORD. 



However, a !ei.'.i ti male '|i'.e-t ion at tin- point would In- : " \\'h,it 

 is the value of al! thi- reconstruction and tln.-c complicated 

 conception- to biolo-ical science and tin- analysis of the organ- 

 ism?" Indeed, this is a (jiic-iion which we have a-k< d onr-elves 

 repeatedly while working through the necessary plant data and 

 all the .-.(-altered unor-.mi/ed literature \\ith which the inve-tiga- 

 tor in thi- line mu-t deal. The question has always been ans- 

 wered in a manner satisfactory to us because whatever value the 

 papers on the ponds of the south end of Lake Michigan and other 

 similar paper- may possess, i- due to the conception of pond 

 succession acquired from the plant ecologists. Had I not ac- 

 quired this knowledge I would have done as others have done- 

 worked this excellent area over without seeing anything in it. 

 The problems that have arisen in connection with this work 

 have given a fresh point of view and a motive for investigation 

 which has repaid the effort. 



In connection with problem- and moiive for their solution, it 

 should be noted that thi- is one of the most important things 

 which the plant ecologists regard as of value in the conception of 

 succession. Cowles, who ha- done more to stimulate work on 

 succession and the use of physiographic method than any oilier 

 American ecologist, regards functional response of plants (deter- 

 mined by watching plants and experimenting on plants) as much 

 more fundamental than succession. Thi- appears to be ^end-ally 

 true of plant ecologists. Warming, who has been a .urcat leader 

 in ecology, emphasizes the physiological side. 



\\'e have, then, amonu ihe workers and originator- of the n-e 

 of this principle, a condition with roped to its place in biolc. \ 

 which is quite different from whal one \\ould expect from .-imply 

 noting what has been the dominant thin- in their work. The 

 relation of the historical and ijeneiic side of ecology to more 

 fundamental physiological and ecological problem-, i- similar to 

 that of the historical and phylogenetic side of evolution, to the 

 problems of biology ami ihe motixe- for in\ estimation. \Vheii 

 Darwin framed the idea <>l evolution into a lo^ic \\hich \\a- not 

 refutable by academic attack, the fails of biology took shape, 

 arranged themselves into orderl} relations to < n-h other. Tin- 

 made possible method- of \\ork \\hich were new. opened up new 



