MULBERRY-DWARF TROUBLES IN JAPAN. 



205 



pounds (ammonium salts or nitrates) in the absence of light, 

 although much more slowly than in full day-light ; the amido- 

 compounds seeming, when the light is insufficient, to be far more 

 conveniently used than the nitrates for the synthesis of proteids. 



It is therefore very probable that the amido-compounds, 

 which are present in the stems and roots of the mulberry, 

 are far more efficiently and quickly used for the formation of 

 new proteids in the growing roots and in the buds where light 

 has no access, and can never be replaced by the inorganic 

 nitrogen compounds absorbed from the soil. 



As can be seen from the tables, the root-bark of Takasuke 

 and that of Tsuruta and Jumonji contained on May 18 and 29 

 respectively (the dates of cutting) only very little reserve 

 materials. The new shoots are therefore compelled to com- 

 mence their development with a very scanty source of reserve 

 materials, so that it may sometimes happen that the reserve 

 materials become exhausted before the new leaves can duly 

 perform their function. The natural result in such a case would 

 be an imperfect development of the leaves, as a consequence of 

 which the assimilation process would be retarded and the 

 nourishment of the new roots become insufficient and their de- 

 velopment be more and more retarded until at last they would 

 be compelled to die off, and the consequent deficient absorption 

 of nutriments from the soil would react injuriously on the leaves. 

 This may be compared to babies deprived of milk and nourished 

 only with solid food, before the digestive organs have developed 

 their powers. Only those plants which have effected a certain 

 degree of development before the exhaution of reserve materials 

 can attain normal growth. 



We can now clearly understand why the variety Jumonji, 

 which requires the least amount of reserve materials as compar- 

 ed witli the other varieties, is so rarely subject to the disease. 



The following calculations will bring out this point more 

 clearly ; — 



A) Takasuke, on April 28, had already developed new leaves, 

 the fiesh weight of which was 282 grams and the 

 dry weight 48.2 grams for one stock, the nitrogen amounting 

 to about 3.072 grams. This nitrogen must have come 

 almost entirely from reserve materials in the stems and 

 roots and not from the soil. Notwithstanding so much con- 



