be noticed. In the case of oats (tables 1-6) absence of potash is marked by 

 the greater severity of the attacks of frit-fly, a state of affairs to be accounted 

 for by the fact, that lack of potash hinders early development, and consequently 

 prolongs the period of susceptibility to attack. The same condition exactly is 

 evidenced where nitrogen or phosphoric acid is present in insufficiency and also 

 where, through various other causes, early growth has been somewhat protracted. 

 The pea plots (tables 7 — 10) shew much more characteristic signs of potash 

 starvation. Not long after the plants, on the plots lacking in potash, are above 

 ground, the leaves exhibit a peculiar lightness of colour, and from this time on- 

 ward the undermost ones wither off with distinctive colour change. The nature of 

 this colour change, as distinct from normal yellowing, is admirably exemplified by 

 Picture 10. 



The symptons again in the case of the sugar-beet (tables 1-3, foreground) are not 

 quite so decisive. The main effects of potash starvation here are darkness of fol- 

 iage and increased tendency to suffer from aphides. The plants at harvest further- 

 more, tend to shew root and leaf in unfavourable proportion, and the root itself 

 to analyse poorer in solids and sugar. The fact that starvation symptoms here, 

 are not so strongly in evidence, is no doubt due to the extreme aptitude of the 

 beet for procuring potash from the soil. 



Especially characteristic indeed is the reaction in the case of potatoes (tables 11-15). 

 In the young plant, lack of potash can be diagnosed by the striking darkness of 



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