in DEVELOPMENT AND ENVIRONMENT 63 



indications of environmental changes, and especially of 

 changes in the condition of the root system. A concise 

 example is provided by the flowering curve of plants 

 growing in the two-metre cylindrical* tanks already 

 mentioned, when compared with similar wide-sown plants 

 growing in ordinary soil near by, and with others growing 

 under the close-sown conditions of the field crop (Fig 44). 

 The curves shown were all taken in the same year, and 

 all from an area of a quarter acre, cultivated in these 

 various ways with the same pure strain. Taking the 



Fig. 44. FLOWERING CURVES. GIZA. 1910. 



Showing root-limitation of tank-plants equally with field-sowings. 

 Note the smaller effect of root-asphyxiation in the wide-sowings. 



wide-sown plants as nearest to normal development, we 

 see that field-planting reduces the number of flowers 

 formed, presumably by the crowding of the flowering 

 branches, and hence reduces the height of the maximum. 

 Comparing these plants with the wide- sown ones grown 

 in the tanks, we find that the ascending flowering curve 

 is checked under the latter conditions, and is not allowed 

 to continue at the normal maximum. Obviously a 

 limiting factor has supervened, and it is more than 

 probable that this factor is the limitation of root-develop- 

 ment through the confinement of the roots within the 

 limited capacity of the tanks. An interesting side issue 



