1 66 



Journal of A gricultural Research vol. xxi, NO. 3 



as those of the green plants. However, the weight of the roots was 

 decidedly less in the chlorotic than in the green plants. This agrees 

 with the field observations, indicating an association between chlorosis 

 and a deficiency of fibrous lateral roots. It will be noted that the 

 strongly chlorotic plants in the vigorous class had a root weight con- 

 siderably less than that of the green plants in the weaker class. While 

 the roots of these plants were also somewhat shorter, the weight differ- 

 ence was distinctly greater. 



The other lack of parallelism between increased chlorosis and de- 

 creased growth is in the primary leaves. These were nearly as well de- 

 veloped in the chlorotic plants as in the green plants. This is considered 

 significant as indicating that the plants which were decidedly chlorotic 

 and lacking in vigor during the second season were not originally very 

 different in their growth rate from the others. This relationship is most 

 easily seen in the three columns under "Relative leaf surface " in Table IV. 



TABLE III. Root, top, and terminal bud development of the different type classes of 



2-year-old seedlings 



UNTREATED WESTERN YEtLOW PINE a 



UNTREATED DOUGLAS FIR 



o The number of chlorotic plants in the treated plots at the end of the season was insufficient to serve as 

 a basis for measurement. 



