696 Howard . — On Diplodia cacaoicola , P. Henn . / 
afterwards distinct infection was noted in No. 2, while in 
Nos. 3 and 4 the trees were nearly ringed near the infection- 
chamber, and the mycelium could be traced in the bast 
and wood as far as six inches above and below this point. 
Pycnidia were noted under the bark near the chamber. The 
control tree showed no infection. 
(d) Attempts to induce infection by spores growing in 
water on the bark, in a manner similar to that used in expe- 
riment 1 (b) above, failed. The spores germinated, but I 
could not detect any penetration of the living tissues by the 
hyphae. 
These infection-experiments show that the Fungus can 
behave as a parasite towards cacao pods, and is a dangerous 
wound-parasite of the cacao tree itself. The nature of one 
of the tree-diseases in Grenada, and of an important pod- 
disease, is therefore placed beyond doubt. 
One Fungus or two? 
Up to this point it had been demonstrated that the Fungi 
on sugar-cane and on the cacao tree, as dealt with above, 
are both capable of pronounced parasitism on their respective 
hosts, and in addition are morphologically identical. It 
became therefore an interesting question to determine whether 
or not parasitism on these widely different hosts had become 
so closely adapted to these hosts that cross-infection was 
impossible. To answer this question the following series 
of infection-experiments was carried out, in which an attempt 
was made to infect cacao trees and pods with pure cultures 
of the sugar-cane Fungus, and also to try the effect of the 
cacao Fungus on the sugar-cane. 
Infection of Cacao Tree and Cacao Pods with the 
Sugar-Cane Fungus. 
(a) Two branches of a healthy cacao tree were infected 
with pure culture-mycelium of the sugar-cane FUngus, while 
a third was used as a control. Four days afterwards the 
