74 
Mycologia 
zoospores are very numerous, as many as twenty issuing from a 
single conidium. The oospores were found in abundance, 
throughout the infected tissue, but no trace of either antheridia 
or oogonia. As subsequent investigators have also failed to find 
the gametes it is now usually conceded that these bodies are in 
reality chlamydospores. The fungus is considered by von Faber 
to be coextensive in distribution with the cacao, although epidemic 
outbreaks have been confined to the American tropics, to Ceylon, 
and to Kamerun. Apparently drawing on von Faber’s account 
of the fungus for his data Maublanc named it P. Faberi. 
Infection experiments were first reported by Rorer (1910 a, b) 
who proved that the pod-rot and the canker of cacao are both 
caused by the same fungus. He gives a detailed study of the 
pathology of the organism, concluding that the trunks become 
infected by the migration of the mycelium from the pods through 
the twigs. This work was confirmed in Ceylon by Petch (1910) 
who extended his experiments to the fruit-rot and canker of 
Hevea. He demonstrated the identity of these diseases. “ On 
plantations of Hevea only * canker ’ has not caused very much 
damage, but on mixed Hevea and cacao plantations it is decidedly 
more serious.” The fungus evidently spreads from the one host 
to the other in the field. 
The correctness of the results obtained by Rorer has been 
questioned by Essed (1912) who was unable to duplicate the 
work. He suggests that the trees used might have already been 
infected with the true cause of the canker, which he considers to 
be some species of Lasidiplodia, Nectria or Spicaria, or some 
other related form. Fie asks “Why should Mr. Rorer obtain 
results different from mine? Was it due to the difference be- 
tween his mode of operation and mine? To be sure, he operated 
with full grown trees and I did so with seedlings; his trees were 
standing in the open field and my seedlings were raised and kept 
under rigorously sterile conditions.” The statement of the case 
by Essed may contain the answer to his inquiry. It is well known 
that certain fungi attacking mature hosts will not attack the 
juvenile stage of the same host plant. The reverse is also true. 
Moreover the “ rigorously sterile conditions ” under which these 
experiments were made might have been so thorough that 
Phytophthora could not grow. 
