Investigations on the Mulberry Tree, 



BY 



N. Maeno, Nogakushi. 



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, - n 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 U 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) Helicobasidimn Mom/a, 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. 



