lipman: plant ecology and soil fertility 321 



writer to be of the greatest importance in studies of any given 

 natural flora like the chapparal formation on the Pacific coast, 

 for example, that we know something regarding the following 

 factors in their relationships with the plants in question. 



1. The proper qualitative nature of the soil solution. 



2. The proper balance between the components thereof. 



3. The proper concentration of the soil solution. 



4. The proper form of nitrogen for the plants. 



5. The influence of quantity and quality of organic matter. 



6. The proper basicity or acidity for the plant. 



7. The mutual influence of plants growing together on their 



welfare. 



Studies on these subjects now being made by the modern special- 

 ist in soil fertility on cultivated plants and by some plant physi- 

 ologists in general can therefore render great aid to the phyto- 

 geographer and plant ecologist in the solution of problems which 

 cannot fail to interest all biologists. 



It is therefore hoped that many cooperative experiments may be 

 established between the plant ecologist and the soils scientist in 

 all parts of this country and elsewhere. Such cooperation will 

 surely redound to the benefit of all the branches of study concerned 

 and to the investigators individually who may be involved in them. 



