DR. DAUBENY ON THE ROTATION OF CROPS, ETC. 



199 



Nicotiana ruslica (Continued). 



The following diagram shows the variations of the crops :- 



Tobacco. 



Years. 



A 



180 



Permanent . 

 170 



160 



150 



140 



130 



120 



110 



100 



90 



80 



70 



60 



50 



Shifting ... 

 40" 



30 



20 



10 



10 



10 



180- 



170 



160 



150 



140 



130 



120 



110 



100 



90 



80 



70 



60 



50 



40 



30 



20 



10. 



►1I)S. 



