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U. SUZUKI. 



ent, unless the development of the new rootlets is exceptionally- 

 good ; and after successive cuttings, the small roots must 

 entirely die off. So it is quite natural that we always find de- 

 cayed roots when the disease is much advanced. But in the 

 earlier stages of the disease, we find only small rootlets dead. 

 The roots and leaves are closely correlated to each other, a bad 

 condition in the one accelerating the degeneration of the 

 other; and the primary cause of the disease must be sought in the 

 practice of cutting in the growing period. 



We see [Plates XIX-XXVI] that the quantity of reserve 

 nitrogen in the roots of Takasuke, Tsuruta etc. is not restored to 

 its norm even in December. This evidently shows a gradual 

 wearing of the plants, and after two or three years, they must 

 become diseased unless they are kept from cutting. 



In the foregoing p:\ges, we have considered only the nitro- 

 gen compounds; but we must remember that the carbohydrates, 

 especially starch, have also the same physiological importance 

 during the first stages of development That the cutting in the 

 growing period, when the starch contents of the roots have 

 reached the minimum, has a specially injurious effect upon the 

 new shoots hardly requires any further explanation. 



The view above developed finds an additional support from 

 the following facts : — 



(i). The disease does not affect those plants which are not 

 cut. This is true throughout the whole country and there is 

 no exception to it. We have observed this in such provinces as 

 Fukushima, Yamagata, Akita, Hyogo.etc, where the cutting meth- 

 od is not practiced. The plants in these provinces attain their 

 maximum height and are 30-40 years, or sometimes even more 

 than 100 years old. Further, we have observed a very instructive 

 case in these provinces, viz. some of the farmers adopted the 

 method of cutting, and all suffered from the disease, while in the 

 neighbouring farms where the method was not adopted the 

 plants were perfectly healthy. A more striking fact was 

 observed in Tanba. A farmer cut the same plants 3 times in one 

 ummer, in consequence of which, all the plants in a farm with- 

 out exception became diseased, while in the neighbouring farm in 

 which the plants were cut only once, the disease did not appear. 

 That the cutting is the principal cause of the disease may also 

 be shown by the fact that, by keeping the diseased plants for 



