ECOLOGY. 339 



gravel to a depth of 8 inches to simulate the original soil conditions of 

 the sere. Simultaneous readings throughout the stations have been 

 made at different levels from time to time of air and soil temperatures, 

 humidity, and light. The readings have been taken at hour intervals 

 for periods of 16 to 18 consecutive hours. The water-content has been 

 determined throughout the summer for each station at different levels. 

 The evaporation has been measured by means of porous-cup atmom- 

 eters, and sunflower and wheat phytometers have been employed to 

 measure the transpiration, photosynthesis, and growth for each habitat. 

 The basic purpose of the quadrat-transect is to determine the annual 

 changes of the plant and animal population and to correlate these with 

 primary succession. In addition, it is invaluable for the study of com- 

 petition and the physiological responses to water and light which are 

 involved in it. The animal population of the several stations has been 

 estimated by various methods. The invertebrates have been counted 

 by using quadrats 4 decimeters square, by sweeping the vegetation for 

 definite periods, and by means of insect traps run simultaneously in the 

 various habitats. 



Transplant Quadrats and Areas, hy F. E. Clements and J. E. Weaver. 



A definite beginning has been made in the application of the methods 

 and principles of experimental vegetation by the establishment of 

 transplant quadrats and areas at Lincoln and Central City, Nebraska, 

 and at Colorado Springs. These have been fenced and equipped with 

 instruments for determining air and soil temperatures, humidity, and 

 evaporation, while determinations of the water-content are made to a 

 depth of 4 feet. The primary objectives of the transplant studies are 

 the comparative equivalence of the dominants of different associa- 

 tions, the conditions under which extral dominants are adopted into 

 the association and the outcome of competition between them. The 

 results will permit the objective determination of the relative impor- 

 tance of migration, physical conditions, competition, and grazing 

 animals and rodents in affecting the invasion of dominants and the 

 permanence of communities. At present, dominants are transplanted 

 as seedlings grown in the greenhouse or as blocks of mature plants. 

 They are planted in areas 0.5 meter square from which the sod has 

 been removed to the depth of 0.5 inch or in tilled areas, and are 

 watered until established. At Lincoln the transplant stations were low 

 prairie, high prairie, and gravel knoll, and both sod and tilled areas 

 were installed in the first two. The species employed were Andro- 

 pogon furcatus, Elymus canadensis, Panicum virgatum, Bouteloua 

 racemosa, Agropyrum spicatum, Poa pratensis, Spartina cynosuroides, 

 Siipa spartea, S. viridula, Andropogon scoparius, Koeleria cristata, 

 Aristida purpurea, Bouteloua gracilis, and Bulbilis dactyloides. More- 

 over, Andropogon hallii, Calamovilfa longifolia, Muhlenhergia pungens, 



