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constructon of tree barriers, even single rowed, but sufficiently thick, ap- 

 pear to be the only means of contending against injurious insects. 



Reckoning the total of all that has been written, we come to the 

 conclusion that the measures against drought which may be adapted by 

 each farmer individually are: the unsparing destruction of weeds on fields 

 throughout the whole year and crop rotations based on the principle not 

 only of a seed change but also of a root change. We saw a proof of 

 the incontestability of these measures in the laws governing the circula- 

 tion of water in the soil, and if we do not reckon with them, it means 

 being always under the threat of drought. The reader is perhaps not 

 satisfied with such a simple solution of the question: but then the truth 

 is always simple. 



