THE DISEASES OF THE SUGAR-CANE. 307 



including Migula/ Went,^ in a bulky paper, has reopened 

 the whole question. According to him sereh is caused by 

 the combined presence of a leafsheath disease due to a 

 fungus, Hypocrea ( Verticilliunt) Sacckari, and a root-disease, 

 bacteria also being incidentally present. It is known that 

 bacteria, which are the cause of so many animal diseases, 

 are not infrequently present in enormous quantities in plant 

 cells without seriously affecting the life of the tissues ; and 

 comparatively few diseases in plants can be traced to their 

 action. It is all the more necessary therefore to exercise 

 caution in attributing any disease among plants to their 

 sole agency. An almost exactly similar controversy has 

 recently been raging concerning imputed bacterial diseases 

 of the vine.^ 



II. The great mass of literature so briefly referred to 

 is of quite recent date. This may be due to the gradual 

 extension to the Tropics of the recent biological activity 

 in Europe. As it becomes more difficult to find subjects 

 for investigation in temperate climates, the overwhelming 

 richness of tropical life in subjects of interest is gradually 

 forced upon one. The earlier observers were unacquainted 

 with parasitic fungi, and their works deal mainly with the 

 insect enemies of the cane.* On the other hand, the 

 presence of trained botanists in the Java Experimental 

 Sugar Stations has resulted in the description of numerous 

 parasitic fungi not recorded elsewhere. Not only have the 

 most destructive forms been carefully studied, but numerous 

 less important discolorations of stems and leaves have been 

 traced to the presence of hyph^ in the tissues.^ There is 

 not the least doubt that many of these diseases, or corre- 

 sponding ones, are present in every sugar-growing country. 



A good deal of attention has always been paid to the 

 insect pests in the Java cane-fields, and a zoologist is 

 specially attached to the East Java Experimental Station. 

 We have, therefore, a long series of papers on insects 



iMigula(i). 2 Went (i). 



^ Prillieux and Delacroix (2). Mangin (i). Schilberszky (i), etc. 



■* Guilding (i) ; Westwood (i) ; Roth (i), etc. 



^Wakker and Went (i). 



