18 



4. Some Comparisons of Seedlings Grown in 

 Water and Soil. 



a. Water Content. The relation of the dry weights to 

 the fresh weights shows a difference in the relative water 

 content of seedlings from seeds of equal size and density 

 grown in water and soil. The percentage of the dry root 

 weight to the fresh root weight is greater for the seedlings 

 grown in soil ; that of the dry shoot and plant weights to the 

 fresh shoot and plant weight is greater for those grown in 

 water. 



The stems of the seedlings grown in soil were brittle 

 while those grown in water could be coiled without 

 breaking. 



b. Roots. The root system of the seedlings grown in 

 soil was very much larger than that of seedlings grown in 

 water. In the majority of the soil culture seedlings the 

 primary root soon ceased to elongate and the main part of 

 the root system consisted of several long, lateral roots aris- 

 ing from near the base of the main root. In the seedlings 

 grown in water the primary root, although comparatively 

 short, was the main part of the root system. Several short 

 lateral roots developed near the base of the root and also 

 lower down on the primary root. 



5. Equation of Growth. 



A study of the tables here recorded shows that the equa- 

 tion of growth given by Blackman, V. H. (1) does not apply 

 to seedlings grown in the dark. In the case of each seed- 

 ling grown under the conditions of these experiments the 

 final dry weight is much less than the initial dry weight of 

 the seed. This would mean, if Blackman's equation held 

 true, that there had been no growth in these seedlings. 



6. Correlation of Weight and Position of Cotyledons. 



Harris (6), in an article on Interrelationships in Phaseo- 

 lus, states that the green and dry weights of the primordial 

 and first compound leaves of plants whose cotyledons are 

 not inserted at the same level of the axis are less than those 

 of normal plants. No such correlation exists for the fresh 

 and dry weights of the seedlings recorded here. Numerous 

 examples of this "abnormality" as Harris calls it, occurred 



