INTRODUCTION 13 



given to some of the early books on gardening, e. g., Parkinson's 

 "Paradisus Terrestris" (1629), which is an account of the orna- 

 mental plants of that period. 



14a. King's book on "The Soil" explains the intimate 

 relation of physical forces to the productivity of the land; and 

 the author is Professor of Agricultural Physics in the University 

 of Wisconsin. There is a Bureau of Soils in the National 

 Department of Agriculture, the work of which is largely in 

 the field of soil physics. The physical or mechanical analysis 

 of soils is now considered to be as important as the chemical 

 analysis. Some of the physical aspects of farm soils are dis- 

 cussed in our chapters ii., iii., iv., v. 



16a. Ecology (written cacology in the dictionaries) is the 

 science which treats of the relationship of organisms (that is, 

 plants and animals) to each other and to their environments. 

 It is animal and vegetable economy, or the general external 

 phenomena of the living world. It has to do with modes and 

 habits of life, as of struggle for existence, migrations and 

 nesting of birds, distribution of animals and plants, influence 

 of climate on organisms, the way in which any plant or animal 

 behaves, and the like. Darwin's works are rich in ecological 

 observations. 



16fe. Environment is the sum of conditions or surroundings 

 or circumstances in which any organism lives. An environment 

 of any plant is the compound condition produced by soil, 

 climate, altitude, struggle for existence, and so on. 



18a. It is customary to consider agricultural chemistry as 

 the fundamental science of agriculture. Works on agricultural 

 chemistry are often called works on agriculture. But agricul- 

 ture has no single fundamental science. Its success, as we 

 have seen, depends upon a union of business methods and the 

 applications of science; and this science, in its turn, is a coordi- 

 nation of many sciences. Chemistry is only one of the sciences 

 which contribute to a better agriculture. Under the inspiration 

 of Davy, Liebig, and their followers, agricultural chemistry made 

 the first great application of science to agriculture; and upon 

 this foundation has grown the experiment-station idea. It is 



