690 Howard. — On Diplodia cacaoicolct , P. Henn. ; 
The Cacao Fungus. 
The Fungus found on the pods and branches of the cacao 
tree agrees, as far as the characters of the pycnidia and spores 
go, exactly with the form described above on the sugar-cane. 
In the case of the pods the pycnidia are often formed singly 
just under the epidermis, and the latter is ruptured by the 
growth of these structures. In diseased branches, or on the 
trunk of the tree, the pycnidia occur usually in colonies just 
under the bark. The appearance of a branch attacked by the 
Fungus, which has been kept in a moist chamber a short time, 
is shown in Fig. 10, and a transverse section through one of 
the colonies is given in Fig. 1 r. 
Some general indication of the appearance of cacao trees 
and pods apparently attacked by this Fungus may be of 
interest. It is quite common in Grenada to see cacao trees 
dying back to a slight extent at the extremities of the 
branches, a phenomenon probably due to poverty of soil, 
wind, drought, or defective root-action, or perhaps to a com- 
bination of these^ causes. In all such cases there is a sharp 
line of demarcation between the dead and living tissues, and 
although several Ascomycetes are to be found in the dead 
wood, they appear to be purely saprophytic in character. In 
many cases, however, dying back goes on to a very great 
extent, extending to the larger branches and the trunk, and, 
in spite of the production of suckers at the base, the trees are 
often killed outright. In such cases there is no boundary line 
between dead and living tissues, but an intermediate zone, 
often as much as two feet in length, always occurs between 
the obviously dead and living tissue. Mycelium can be easily 
detected in the young wood in this transition-region, and the 
pycnidia referred to above are to be found under the bark. 
The mycelium can be detected in the wood at some distance 
in advance of the point at which it seems to end in the bast, 
a point which seems to indicate the saprophytic origin of the 
Fungus. The mycelium makes its way in the wood from 
element to element by means of the pits in the walls of the 
