4 THE FOUNDATION OF ECOLOGY 



the small numb-er of successions so far studied. Future prog'ress in this 

 field will be conditioned not only by the more frequent study of develop- 

 niental problems by working ecologists, but also, and most especially, by 

 the application of known principles of succession, and by the working out 

 of new ones. 



6. Ecological phytogeography. Until recent years, the almost universal 

 tendency was to give attention to formations from the standpoint of vegeta- 

 tion alone. While the habitat was touched here and there by isolated work- 

 ers, and plant functions were being studied intensively by physiologists, 

 both were practically ignored by ecologists as a class. The appearance of 

 Warming's Lehrbuch der oecologischen PHanzengeographie (1896) and of 

 Schimper's Pflansengeographie auf physiologischer Grundlage (1898) rem- 

 edied this condition in a measure by a general discussion of the habitat, and by 

 emphasizing the importance of the ecological or physiological point of view. 

 Despite their frank recognition of the unique value of the habitat, the major 

 part of both books was necessarily given to what may be termed the general 

 description of formations. For this reason, and for others arising out of 

 an almost complete dearth of methods of investigation, ecology is still al- 

 most entirely a floristic study in practice, although there is a universal recog- 

 nition of the much greater value of the viewpoint which rests upon the 

 relation between the formation and its habitat. 



7. Experimental ecology. Properly speaking, the experimental study of 

 ecology dates from Bonnier^ (1890, 1895), though it is well understood that 

 experimental adjustment of plants to certain physical factors had been the 

 subject of investigation before this time. The chief merit of Bonnier's 

 work, however, lies in the fact that it was done out of doors, under natural 

 conditions, and for these reasons it should be regarded as the real begin- 

 ning of this subject. Bonnier's experiments were made for the purpose of 

 determining the effect of altitude. Culture plots of certain species were 

 located in the Alps and the Pyrenees, and the results were compared with 

 control cultures made in the lowlands about Paris. In 1894 he also made 



' Bonnier, G. 



Les Plantes Arctiques Compar^es aux Mimes Especes des Alps et des Pyrdn^es. 



Rev. Gen. Bot. 6:505. 1894. 

 Cultures Expdrimentales dans les Alps et les Pyr^n^es. Rev. Gen. Bot. 2:514. 1890, 

 Recherches Exp^rimentales sur I'Adaptation des Plantes au Climat Alpin. Ann. 

 Nat. Sci. 7:20:218. 1895. 

 Bonnier, G., et Ch. Flahault 



Modifications des v^g^taux sur I'influence des conditions physiques du milieu. 

 Ann. Nat. Sci. 6:7:93. 1878. 



