378 



Soil Factors on Disease Resistance 



aeration and produces root asphyxiation. Soon after the monsoon begins 

 in June, the level of the rivers rise followed by that of the ground water. 

 The movements of the river levels and the general ground water are 

 illustrated by the curves shown in Fig. 1, which represent the state of 

 affairs of the river at Pusa and of one of the wells (about a quarter of 

 a mile distant) for the years 1910 and 1912. 



The curves are typical of the subsoil water conditions of North Bihar 



JAN. MAR. MAY JULY SEPT. NOV. 

 FEB. APR. JUNE AUG. OCT. DEC. 



JAN. MAR. MAY JULY SEPT. NOV. 

 FEB. APR. JUNE AUG. OCT. DEC. 



Fig. 1. Changes in the river and well levels at Pusa. 



The well levels are shown by dotted lines. The observations are 



expressed in feet above mean sea-level. 



Table I. Percentage of C0 2 in the Soil Gas from three different plots 

 in the Botanical Area, Pusa, in 191 9 1 . 



I am indebted to Mr Jatindranath Mukherji for these determinations. 



