300 SCIENCE PROGRESS. 



discoloured patches appear upon the joints halfway up the 

 stem. The tissues beneath these spots are seen to be red 

 or brown, and are found to have lost their sweet taste. 

 Examination under the microscope shows the cells to be 

 penetrated in all directions by the hyphae of a fungus. A 

 little later, black eruptions are noticed on various parts of 

 the stem, especially near the tips of the sleeping adven- 

 titious roots, which form a zone at the base of each joint. 

 Fine, curled, black threads are emitted at these points. 

 A microscopic examination of these threads reveals count- 

 less conidia united together by a mucilaginous matrix. 

 This is the common or Melayiconitun stage of Triclio- 

 sphaeria SacchmH. The disease is particularly harassing 

 because it does not declare itself till the year's agricultural 

 work is done and there is the promise of an abundant 

 harvest. It spreads with incredible rapidity, and the canes, 

 if not immediately cut, fast deteriorate, until, in bad cases, 

 they are not worth the cost of reaping. 



6. In all parts of the Tropics, further, there are numerous 

 animal parasites on the canes. It is difficult to give an idea 

 of their numbers or to form an estimate of the damage in- 

 flicted by them. Occasionally one of them increases to the 

 proportions of a plague — witness the locusts of the present 

 season in Natal — but their destructiveness just now seems 

 to be secondary to that of the fungoid and bacterial diseases. 

 There remains much to be done before our entomological 

 knowledge of the cane-fields is at all complete. Here and 

 there detailed studies have been commenced ; and there 

 seems some prospect of this being continued in East Java, 

 where an entomologist is attached to the Experimental 

 Sugar Station. One author enumerates between sixty and 

 seventy species of insects known by him to be injurious in 

 the Java cane-fields: six beetles, six "borers," twenty-five 

 other grubs, several grass-hoppers, four thrips, a number of 

 scale-insects, four or five cicadae, etc., etc.^ 



Most formidable in destructive power, and widest in 

 geographical range is the "moth-borer," Diatraea saccliaralis 



^ Kobus (i). 



