RECENT INVESTIGATIONS. 31 



much discussed in Chapters VII and VIII, and his investigations of English 

 vegetation are abstracted in Chapter XI. Hence it will suffice here to point 

 out that his concept of the formation was first advanced in 1907 (12), devel- 

 oped in 1910, and applied to the vegetation of the Peak district in 1913. 



Clements, 1910.— In the "Life History of Lodgepole Burn Forests," Clem- 

 ents endeavored to lay down a set of principles and to furnish a model for the 

 exact study of succession by means of instruments and quadrats. Apart 

 from the use of the latter, especial emphasis was placed upon the method of 

 reconstructing the history of a burned area by means of the annual rings of 

 woody plants and perennials, and by means of fire-scars and soil-layers. 

 Seed production, distribution, and germination were regarded as the critical 

 points of attack, and the consumption of seeds and fruits by rodents and birds 

 was held to be of paramount importance. Reaction and competition were 

 studied quantitatively for the first time in successional investigation, and 

 these were related to the rate of growth and of development. 



Cowles, 1911. — In "The Causes of Vegetative Cycles," Cowles performed 

 a distinct service in drawing attention clearly to the three great causes of 

 succession, namely, climate, physiography, and biota. While the importance 

 of these had been recognized (Pound and Clements, 1898 : 218; 1900 : 317; 

 Clements, 1904 : 124), they had not been used for the primary groups in classi- 

 fication, nor had their developmental relations been emphasized. While it 

 is repeatedly stated in the following chapters that the causal grouping of seres 

 is less fundamental and satisfactory than a developmental one, there can be 

 no question of its attractiveness and convenience. In fact, it is a necessary 

 though not the chief part of a consistently developmental classification. 

 Cowles's ideas are discussed at some length in Chapters VII, VIII, and IX, 

 and hence only the main topics of his treatment are indicated here. 



1.' Demonstration of vegetative cycles. 



2. Development of djmamic plant geog- 



raphy. 



3. Delimitation of successional factors. 



4. Regional successions. 



5. Topographic successions. 



6. Biotic successions. 



7. Conclusion. 



Shantz, 1911.— In his paper upon "Natural Vegetation as an Indicator," 

 Shantz gave the results of the first quantitative study of the reactions and 

 successions of a great grassland vegetation. In addition, his studies furnished 

 convincing proof of the basic importance of instrumental and quadrat methods 

 in investigation, and yielded practical results in a new field of the first conse- 

 quence. The study of water penetration, of the relation of root systems to 

 it, and of the influence of developing vegetation upon it was a brilliant analysis 

 of reaction, and will long sei-ve as a model for all investigators. The graphic 

 representation of these relations in a double transect, or "bisect," constitutes 

 a new method of record of great value. The detailed account of this paper 

 is found in Chapter X. 



Tansley, 1911. — Tansley and his colleagues, in "Types of British Vegeta- 

 tion," were the first to apply the developmental concept to the treatment of 

 a great vegetation. Moss's concept of the formation was used in organizing 

 the material, and this, combined with a thorough understanding of the basic 

 importance of succession, gave to the treatment a distinctively developmental 

 character. In this respect, the book is practically unrivaled among accounts 

 of extensive vegetations, and its value must always remain great, even if the 



