ECOLOGY. 295 



successional indicators, and the application of this to practical prob- 

 lems in grazing and forestry. The vegetation studies of the six years 

 have afforded such justification of the developmental treatment of 

 formations and its basic importance for indicator purposes that a 

 fairly extensive account of the cUmax formations and their associa- 

 tions has been given in the monograph on indicator plants. 



Climatic Cycles, by F. E. Clements and A. E. Douglass. 



The investigation of climatic cycles has been continued from both 

 the biological and astronomical approach. The former gains interest 

 from the fact that the years 1916, 1917, and 1918 have in general 

 been years of drought in the West and especially the Southwest. 

 This was suggested as a probability upon the approach of the sun-spot 

 maximum in 1916. The maximum was passed in 1917, and attention 

 is now centered upon the expected increase of rainfall generally as 

 the sun-spot minimum is approached during the next four or five 

 years. It is proposed to follow the biological effects as seen in growth, 

 reproduction, and abundance as closely as possible and to correlate 

 these with the climatic phases. Striking evidences of these effects 

 have been obtained during the drought of the past two years. By 

 far the most important problem, however, is the relation of the sun- 

 spot cycle to the climatic and growth cycles. There appears to be 

 little question of the usual coincidence of these three cycles, but the 

 existence of a causal relation is still in doubt. In the endeavor to 

 make use of the sun-spot cycle to anticipate climatic changes, this 

 matter is of paramount importance. For this reason, a re-examination 

 has been made of the pine and Sequoia sections upon which the orig- 

 inal conclusions were based. New material has also been secured 

 from the Sequoia forests during the present summer for the purpose of 

 resolving several doubtful points. In addition, it is hoped to extend 

 the correlation of tree growth and sun-spot cycles into the geological 

 past by the examination of sections of fossil trees from different 

 periods. The biological aspects of climatic cycles are discussed in the 

 monograph on indicator plants. It is proposed to prepare a detailed 

 summary of all the results so far obtained in the study of sun-spot 

 cycles and climatic cycles, and in particular of the evidence obtained 

 from the growth of trees. 



Permanent Quadrats, by F. E. Clements, Edith Clements, and G. V. Loftfield. 



The progress in the study of climax formations and their succes- 

 sions has made it increasingly evident that the method of observation 

 and comparison is approaching its limit of usefulness (Clements, 

 1916, p. 423). To reduce the personal equation to the minimum and 

 to eliminate interpretation as much as possible, it is necessary to devise 

 a method by which climate and vegetation furnish their own record 



