144 



which can change to a yellowish tinge under the influence 

 of the sap of the tree; thèse layers frequently encircle 

 the entire surface of smaller roots, kiUing the cambium 

 layer, and consisting of extremely fine hyphae (diameter 

 IV2 — 2V2 y) somewhat fatty in appearance; and when 

 fresh material is taken from the roots and examined in 

 water, alcohol or hydrate of chloral, it shows no septae 

 at an enlargment of 740. On the external side of the 

 bark rhizomorphs are found, but in no profusion; they 

 develop lengthwise, branching out occasionally, are fre- 

 quently flattened and black in colour with a white heart. 



In this connection the fungus slightly resembles Armil- 

 laria mellea (Vahl) Quel, in Europe. In a former 

 publication of W a r b u r g discussing the so-called „ Cinchona 

 root-canker" ^), the writer mentions also having found 

 rhizomorphs resembHng at times those of Armillaria. 



When inspecting the fungi generally, especially those 

 growing on decaying or dead stumps of wood-trees on 

 the Cinchona plantations, it is almost an impossibility to 

 discover the true fruit form or forms of the white root- 

 fungus, however it seemed to me important, not only as 

 a matter of scientifîc interest, but also for the culture of 

 the Cinchona, to trace the fruit form of this fungus, so 

 that de toadstools could be destroyed, as is done with 

 the Armillaria mellea in Europe. The safest way was 

 therefore to start from pure cultures and to get to the 

 fruit form in that way. For this purpose I selected 

 diseased roots of Cinchona which were thoroughly cleaned 

 and brushed under the flow of the water tap, then dipped 

 into alcohol and set light to, so as to take away ail 



') O. Warburg. Beitrag zur Kenntnis der Krebskrankheit der China- 

 baume auf java. Ber. d. Ges. f. Botanik zu Hamburg Heft III 1887. 



O. Warburg. Bijdrage tôt de kennis van den kanker der Kinaboomen. 

 Tijdschrift voor Nijverheid en Landbouw in Nederl. Indië. Deel 35,; 

 1887 blz. 195. 



