Winifred E. Brknciiley 



215 



season of the year, it is often impossible to get satisfactory germination 

 of barley, as root development is usually inhibited, and even if seedlings 

 are obtained the young plants make very little growth. Consequently 



Weight 

 Grams 

 801- 



Temp 



"F. 



100° 50 

 90' 

 80° 40 

 70° 

 60° 30 

 50° 



40° 20 

 30" 



2O°10 

 10° 



Sunshine 

 Hours 



400 



300 



200 



100 



Fig. 3. Graph showing relations between total growth, total hours of sunshine and the 

 range of mean maximum and minimum temperatures for several series of pea plants 

 grown in water culture at different times of the year. All series were grown for 11 weeks 

 except 0, in which the plants died prematurely at the end of seven weeks. 

 Nutrient solutions changed weekly. 



Heavy line =total growth. 



Dotted line = total hours of sunshine. 



Upper light line = range of maximum temperatures. 



Lower light line=range of minimum temperatures. 



peas were selected, for although the individuality of the plants is rather 

 more marked, seedlings can be obtained throughout the winter, and a 

 certain amount of growth can be relied on at whatever time the experi- 



