ECOLOGY. 347 



Soil Fauna, by G. W. Goldsmith. 



The work has been extended to include typical habitats from the alpine 

 meadows to the plains. A large part of the soil fauna of the alpine meadows 

 is composed of nematodes, which occur most abundantly within 2.5 cm. of 

 the surface. In the warmer and drier soils of the plains this surface layer 

 contains comparatively few forms, the majority being found at a depth of a 

 decimeter or more. The cultivated soils show a similar summer distribution, 

 the greater portion of the animals being found below the layer of cultivation. 



The task of checking the efficiency of the methods employed in obtaining 

 the soil organisms has received further attention. At 50° C. the extraction 

 must be continued for at least 24 hours to be complete, when 2 cm. of soil are 

 distributed in three 12-inch funnels. A number of organisms are removed 

 from the soil during the first hour, their reaction apparently being due to 

 temperature. The remaining animals, however, do not behave in the same 

 way and are only removed several hours later upon the drying-out of the soil, 

 evidently in response to drought. No conspicuous group reactions of Acarina, 

 Chilopoda, or Thysanura are noticeable. The time required for extraction is 

 reduced by a smaller amount of soil, by increased temperature, lower water- 

 content, and less compact soil, the most rapid results being obtained with 

 loose, dry duff, the slowest with wet clay. 



Climax Formations, by F. E. Clements and E. S. Clements. 

 The grassland formation has again received the major attention because of 

 its great extent, climatic significance, and economic importance, but much 

 attention has been paid to the three scrub climaxes — desert scrub, sagebrush, 

 and chaparral — and some has been given to montane and subalpine forest. 

 The subclimax prairie was studied from eastern Nebraska to northern Texas, 

 the true prairie in southern Nebraska and northern Kansas, the mixed prairie 

 from Colorado through Wyoming into western Nebraska and through north- 

 ern and central Texas, the desert plains from western Texas to the edge of 

 the Colorado Desert, and the bunch-grass prairie throughout southern and 

 central Cahfornia. In the subchmax prairie special attention was devoted to 

 the rank of dominants, the contact with the true praiiie, and the climatic 

 relation to the edge of the forest climax. Conclusive evidence of a wide range 

 was obtained to the effect that this association, as its name indicates, occupies 

 a region capable climatically of supporting forest, as is indicated by the fact 

 that the rainfall averages from 35 to 40 inches. In Texas the mixed prairie 

 was found in contact with the subclimax one, the true prairie dropping out in 

 Oklahoma. The overwhelming evidence that short-grass plains are mixed 

 prairie modified by grazing was greatly augmented, all pastures and over- 

 grazed areas in this association being pure buffalo-grass sod in Texas and a 

 mixed sod of this and grama in Colorado and Kansas. Sporobolus cryptandrus 

 was found to be one of the chief dominants of both mixed prairie and desert 

 plains, though, like Stipa, one of the first to be grazed out by cattle and rodents. 

 The season was especially favorable to the grama grasses, and demonstrated 

 that the desert plain is primarily a Bouteloua association, B. eriopoda being 

 the most important dominant, followed by gracilis, hirsuta, racemosa, bro- 

 moides, rothrocki, and trifida. The serai relations of the bunch-grass prairie 



