692 



Therefore, a greater abundance of ash in proportion to the organic 

 substances produced, as has been emphasized already as typical for all 

 defective plants. 



The characteristic of the shrivelling disease of the mulberry is a con- 

 gestion of starch in the diseased leaves and a very scanty development of 

 the wood body, especially of. the conducting elements, the sieve tubes. Be- 

 cause of the scanty number and small breadth of the lumina of these 

 elements, only a ver}' slow transportation of the assimilated material (here 

 especially sugar) can take place. Consequently the continued dissolution 

 of the starch is prevented^ Besides these anatomical conditions, chemistry 

 now proves the presence of an abnormally large quantity of oxydases and 

 peroxydases. According to Woods, it is very probable that the oxydases 

 not only destroy all the chlorophyll but also prevent diastatic and proteo- 

 lytic action. On this account, they might be the cause of the delay in the 

 transportation of the starch and nitrogen compounds. At any rate, Shibata- 

 maintains, as a result of his experiments, that the diastase action is not pre- 

 vented by the oxydase and that a further production of the enzymes would 

 be caused by the entire elimination of the elaborated materials. Later 

 experiments must make clear which of these theories is correct. The fact 

 is sufficient for us here that the zvhole amount of the reserve substances is 

 exhausted in the sick plants''. This is shown also in the scanty filling with 

 starch of the bark on the branches and roots and of the dormant buds, and 

 manifests itself also in the decrease of root pressure and the transpiratory 

 intensity (Miyoshi). It is now clear that if a plant is continually forced to 

 use its reserve material by the removal of its foliage, it does not have time 

 enough to mature the new growth, i. e., to deposit sufficient starch, albumen 

 and cellulose in these organs. 



The curing of this disease will lie in a return to the normal fall pruning. 

 As soon as branches of diseased plants have developed their own roots by 

 layering, they develop normally as Suzuki has shown experimentally. 



Besides this, very similar phenomena of disease also occur in the tea 

 plant as soon as the picking of the leaves is carried on irrationally. 



The Sereh Disease of the Sugar Cane. 



At present the Sereh disease, which appeared in Java in the 8o's of the 

 last century and is advancing from the West to the East, is, indeed, the 

 most greatly dreaded disease of the sugar cane. It has now been observed 

 also in Reunion, Sumatra, Borneo, Malakka, the Mascarrean Islands, and 

 in Australia*. According to Kriiger", whom we follow first of all, the name 



1 Miyoshi, M., Untersuchung'en iiber Schrumpfkrankheit ("Ishikubyo") des 

 Maulbeerbaumes. II. Journ. Coll. Sc. Tokio 1901, Vol. XV. 



2 Shibata, K., Die Enzymbildung in schrumpkranken Maulbeerbaumen. The 

 Botanical Magazine XVII, 1903. 



3 Suzuki, loc. cit., p. 277. 



4 Cit. Zeitschr. f. Pflanzenkrankh. 1901, p. 297. 



5 Kriig-er, W., ffber Krankheiten u. Feinde des Zuckerrohrs. Ber. d. Versuchs- 

 station f. Zuckerrohr in West -Java, Kagok-Tegal. Dresden, Schonfeld's Verlag, 

 1890, p. 126. 



