Investigations on the Mulberry Tree. 
BY 
N. lYTaeno, Nögakushi. 
I. Improvements in the Quality of Mulberry 
Leaves by a Special Manure. 
It is a fact that in certain provinces of Japan a better silk is 
produced than in others, although the silk worm is sometimes of 
the same variety. It may be surmised that the nature of the soil 
exerts much influence on the quality of the leaves used as food 
by the caterpillar. The relative amount of digestible and indi¬ 
gestible material in mulberry leaves must naturally have a 
certain bearing upon the well-being of the silkworms and hence 
also upon the quality of the thread produced. This led me to in¬ 
stitute some experiments with the intention of attaining a decrease 
in the amount of woody fibre and especially an increase in the 
amount of proteid and fat. I supposed that manuring with lime, 
calcium sulphate, and sodium nitrate would be especially well 
adapted for the production of such a superior quality of leaves, 
and thought it best to apply lime in the form of slaked lime, hop¬ 
ing thereby also to destroy the mycelium of a very noxious 
fungus, (1) found in our mulberry plantation at the College of Agri¬ 
culture in Tokyo. 
The soil consists here principally of volcanic ash mixed with 
sand, and contains from 7-8 % humus. It is rather poor in lime 
and sulphates and had received, one year before I commenced 
my experiment, a moderate dose of night soil as manure for the 
trees. I manured a mulberry tree about 1^ meter high with 500 
grams lime, 400 grms. sodium nitrate and 200 grms. calcium 
sulphate (2) in the beginning of March (A), while another tree was 
manured with 500 grms. lime alone (B) ; a neighbouring tree re¬ 
ceived no manure and served for comparison (C). 
(1) Helicobasidium Mompa, studied by Tanaka , Journal of the College of Science, 
Tokyo, Vol. IX. 
(2) These materials were well mixed with the soil to a depth of about 30 cm. and to 
an extent of one square meter around the tree. I wanted to have phosphoric acid, 
potassa, and magnesia in the minimum, and supposed there was some left in the soil 
from the year before. 
