43 



of this case." „It seems to me, we hâve to do with one 

 of those cases, where a disease, when first appearing, 

 takes a very serious aspect and then gradually looses 

 groLind, or in other words, where the infection at first is 

 very virulent and so spreads easily, while the virus by 

 and by looses much of its power." 



„That the canker is very virulent in the beginning of 

 its appearance, is in my opinion proved by a case, which 

 I noticed this year for the first time and that in a 

 single spot of the plantation. But in this spot every tree 

 was found to be affected, a thing which does not occur 

 on estâtes where the canker has been présent for years." 

 On one estate Zehntner found the fructification of the 

 cankerfungus (probably Nectria). 



Finally in 1907 von FaberO noticed the disease in 

 the Cameroons, where up till now, it has not caused 

 much damage. There also a Nectria has been found on 

 the diseased bark. 



Anatomical Investigation. 



On microscopical examination every red spot of the 

 diseased bark appears to be surrounded by a corkcam- 

 bium, several rows of cells thick (Fig. 4). The colour is the 

 resuit of a red coloured mass in the cells. This is often 

 transparent and fil! s up the cells completely, but it may 

 be granular or form smaller or larger drops, which some- 

 times flow together along the cellwalls, forming irregular 

 masses. The cellwalls too are often coloured, and the in- 

 tercellular spaces filled up with it. In the first celllayers 

 within the corkcambium the colour is not red but brown ; 



1) F. C. von Faber. Untersuchungen ûber Krankheiten des 

 Kakaos. Arbeiten aus der Kaiserl. Biolog. Anstalt ftir Land- und 

 Forstwirtschaft. Band VI. 1908. p. 395. 



