MULBERRY-DWARF TROUBLES IN JAPAN. 



171 



pointed out by some as the cause of the disease, and ascribed to 

 mirco-organisms. But as observations were extended it became 

 apparent that this decay of the roots is not the cause of the 

 disease, but only a secondary phenomenon, due to want of nourish- 

 ment ; and we see that in the first stages of the affection, the 

 roots do not show any perceptible difference from those of healthy 

 plants, and only when the disease becomes more advanced 

 do the roots decay. If the decay of the roots be the cause of the 

 disease and due to micro-organisms, then it is hard to understand 

 why the disease is almost confined to plants subjected to cutting, 

 while those that are left to their natural growth are entirely free 

 from it. The explanation appears to me to be that the decay of 

 the roots is a result of the disease just as the imperfect growth of 

 the leaves, and that both are effects of some underlying cause. 



I shall not give a detailed diagnosis of the disease, and the 

 reader is referred to the accompanying photographic reproduc- 

 tions. Numerous figures are also given in the chapter on the 

 comparative analyses of healthy and affected plants, which have 

 been made particularly exact and are thought sufficient to bring 

 out the characteristics of the disease. 



Previous to the appointment of the board before mentioned, 

 several persons have been engaged on the same problem, but it 

 is thought unnecessary to detail the results obtained by them. 

 We must, however, acknowledge our indebtedness to the results 

 obtained by Messrs. Ichikawa and Hori in the Agricultural Ex- 

 periment Station of Aichi Prefecture, which are largely cited in 

 the present paper. An extended inspection in different localities 

 has convinced me that the present disease is confined to those 

 plants which have been subjected to cutting; hence I was led to 

 inquire into the effect of cutting on the plant. I found that during 

 the growing period the reserve materials in the barks of the roots 

 and stems are all transported to the growing parts and reach 

 the minimum, and therefore if the plants are cut down in this 

 period the new shoots would be forced to depend on an exceed- 

 ingly small quantity of reserve materials. Hence the leaves 

 would be only imperfectly developed, and the reserve materials 

 would be exhausted before the plants can absorb and assimilate 

 adequate nourishment from the soil and the atmosphere. Hence 

 I concluded that the primary cause of the disease is to be sought 

 in the practice now in vogue of subjecting the mulberry to re- 



