460 JOURNAL OF FORKSTRY 



With these low prices and a confined market, the forest service, 

 nevertheless, manages with an expense of around $40,000, to make a 

 net return of $120,000. 



Revue des Eaux et Forets, August, 191 7, pp. 225-228. 



BOTANY AND ZOOLOGY 



Two recent papers on plant ecology are worthy 

 Structure and of consideration by American silviculturists, par- 

 Developmcnt ticularly those interested in the foundations of 

 of the Plant silviculture or silvics. Gleason's paper takes 

 Association issue with Clements' recent monograph on suc- 



cession : (a) In considering the unit of vegeta- 

 tion an organism; {b) in considering the unit of vegetation a climax 

 and all the successional series leading to the climax; (c) in the com- 

 plexity of the unit due to (a) and {h) ; {d) in the apparent exceptions, 

 excluded from the unit by the limitations of the definition. 



Most silviculturists will agree with the author that the analytical ex- 

 position of vegetation by Clements is too complex and too much over- 

 burdened by terminology. Gleason offers a series of general principles 

 explanatory of the usual phenomena of vegetation and derived chiefly 

 from his own observation. He states that these principles were de- 

 rived synthetically rather than analytically. The principles enumerated 

 are 28 in number, few of which are supported by illustration. They 

 are embraced under the following heads : 

 (a) The individual concept of ecology. 

 (&) The environment. 

 ic) Migration and selection. 



(d) The association, its size and boundaries. 



(e) The structure of the association. 

 (/) Scope of the association. 



{g) Succession. 



Under "The individualistic concept of ecology," the author states: 



"The phenomena of vegetation depend completely upon the phe- 

 nomena of the individual. It is in sharp contrast with the view of 

 Clements that the unit of vegetation is an organism, which exhibits a 

 series of functions distinct from those of the individual and within 

 which the individual plants play a part as subsidiary to the whole as 

 that of a single tracheid within a tree. 



"It is true that various analogies may easily be drawn between a unit 

 of vegetation and an organism, but these analogies are always more 

 apparent than real and never rise to the rank of homologies. For ex- 



