LM<) Jh'lations hefuwcn (h'oirfh (iihI hJurironmcnf 



nients are started. A dwarf variety, "Sutton's Harbinger," were used 

 for the majority of the tests, but as unfortunately the stock ran out and 

 could not be replaced the last four tests had to be carried out with 

 Sutton's "King of the Dwarfs^." 



The seeds were graded and ranged between •25--3 gnis. or '?>--?>h gms. 

 for '• Harbinger," and -^--SS gnis. or -35 --4 gms. for " King of the Dwarfs," 

 only one range of weights being used in each test. At intervals of a few 

 weeks sets of IGO ])ea seedlings were put into water cultures. Usually 

 two parallel tests were carried out, in one of which the nutrient solution - 

 was changed weekly and in the other the original solution was retained 

 throughout the experiment. The same day that the water cultures were 

 set up ten extra seedlings were prepared for drying, in order to obtain 

 the initial dry weight of the plants. In addition 10 seeds of the grade 

 used were weighed, to give the relation between seed and seedling after 

 germination. At regular weekly intervals 10 plants from each set were 

 removed from their solutions and the roots carefully washed two or 

 three times in clean water to remove adherent food salts. The roots and 

 shoots were separated before drying, and when the plants were in the 

 fruiting stage the pods were removed, and dried and weighed separately. 

 The 10 plants taken each week were selected at random from the whole 

 group, and may be considered to represent more or less accurately the 

 average growth of any similar number of plants at the time. The figures 

 thus obtained were graphed, and the data yield valuable information 

 as to the rate of growth of the pea plant and its relation to certain en- 

 vironmental conditions. 



A. Nutrient Solutions changed weekly 

 The constant change of the nutrient solution ensured that a plentiful 

 supply of food was always available and that starvation effects did not 

 manifest themselves. The supply of water was maintained by replacing 

 that which was lost from the bottles by transpiration from the leaves, 

 and as the tests were carried out in the greenhouse the plants were not 



' Our thanks arc due to Mr Martin Sutton for the u'ift of all tlie seeds used throughout 

 tliesc experinionts. 

 - Nutrient sohition: 



Potassium nitrate ... ... 1 gin. 



Magnesium suljjhate ... ... •.") 



Calcium sulphate ... ... ■"> „ 



Sodium chloride ... ... -A ,, 



Potassium di-hydrogen pliosjiliatc -."i „ 

 Ferric chloride ... ... ... 04 „ 



Distilled water to make iii> I lilt<'. 



