60 THE POTATO CROP. 



many years past, more and more from the natural con- 

 ditions of its healthy growth ; and it has paid the penalty 

 of high cultivation by a debilitated constitution and a 

 tendency to disease which in its normal state did not 

 exist. Selected tubers, a deep dry soil, long intervals be- 

 tween the recurrence of the crop on the same ground, 

 and the absence of rich stimulating manures, would no 

 doubt do much towards restoring its general health and 

 vigour, or, at all events, in arresting the further diminu- 

 tion of its powers ; but then we should have to content 

 ourselves with diminished returns ; and, in the competi- 

 tion of our present production, there are few probably who 

 will not think the remedy worse than the risk. 



These same causes of deterioration are already affect- 

 ing our regular root crops ; our turnips have been visibly 

 declining in general health and vigour for some few 

 years past; and there is but little doubt our mangolds 

 will in the course of time follow in the same way. These 

 are both comparatively recent introductions to the potato. 

 The great injury, however, has doubtless been inflicted 

 during the last twenty or thirty years, when increased 

 cultivation and production appear to have been accom- 

 panied by the anomalous conditions of increased neglect of 

 the general laws and principles governing vegetable life, 

 and of the natural habits and requirements of the plants 

 we rely upon for our daily supplies of food. Attention to 

 these is far more important for the prevention of diseases 

 than any remedies that may be devised for their cure. We 

 have ample evidence of this throughout the whole king- 

 dom of organic nature ; and we can adduce no more pro- 

 minent instance of its truth and force than is seen in the 

 potato and the disease now affecting it. 



The number of insects known to us as infesting and more 

 or less injuring the potato crop, is fully as large as that 

 met with in either the wheat or the turnip crops. At the 



