THE TROPICAL AGRICULTURIST. 
[June t, 1898. 
SS2 
other facta of importance in this connection are that 
trees, which are badly attacked, if cut down to 
within a few inches of the ground will produce 
from the remaining portion of the stem suckers 
which are perfectly healthy and produce sound leaves 
and fruit ; also that seedlings planted only a few 
inches from a badly diseased tree — 30 that their 
respective roots must be iutennatted and touch at 
many points — grow vigorously without any signs of 
disease. These facts lead me to the opinion which, 
I think, I shall farther prove in this report that the 
disease does not affect the roots. 
On coming to the examination of the stem and 
branches in diseased trees, patches on the bark can 
be observed with the naked eye, in some places 
claret-coloured drops exume from the bark, and where 
these drops had presumably run over the surface, a 
characteristic rusty skin is produced, the patches were 
darker in colour and damp to the touch, and on cutting 
into them the tissues are found to be discoloured, 
their natural colour being changed to a neutral tint 
or claret colour. On examining these portions mi- 
croscopically the tissues are found to contain the 
mvcelium (that is the vegetative portion) of a fungus, 
and also in large quantities bodies of more or less 
gpherical shape, the nature of which I at first 
thought to be fungal, through a certain resemb'auce 
to tile rest spores found among certain groups of 
these plants — they, however, can be dissolved in hy- 
drochloric acid, and therefore I consider them to be 
cluster-crystals of Oxalate of Lime, the nature of 
which I am investigating and hope to elucidate. 
These bodies, however, have no connection with the 
fungus and are therefore of less importance. 
The leaves are free from fungi and, in cases of a 
tree having died from disease, present all the appear- 
ances on microscopic examination, that the leaves of 
a tree’ dying from want of moisture would have, thus 
showing that there is no disease in the leaf, but that 
the death of the stem having cut off the supply of 
nutrition from the root, the leaves have died with 
the rest of the tree 
On coming to the fruit I noticed a very large number 
of dead and diseased pods of all sizes from an inch 
long, many of which were covered with saprophytic 
fungi and had died from causes which I hope at some 
future time to discuss ; but others — and these the 
larger ones — were attacked by a disease which, from 
its occurrence on trees otherwise absolutely healthy 
and from its non-occurrence on cankered trees, I 
came to the conclusion has no connection with the 
canker, and the experiments which are afterwards des- 
cribed support this view. - . j ^ 
The disease can easily be distinguished from the 
blackening of pods owing to drought or Hc-lopeltis. 
It begins either at the point or at the stalk of the 
pod, almost never (about once in a hundred) in the 
middle, and creeps along the pod showing a well- 
defined boundary of brown tissue encroaching on the 
yellow, red or green healthy tissues of the pod. If 
the po’d is cut this will be found to discolour the 
whole of the tissue not to be merely a superficial 
injury as in some other cases of browning or 
blackening. 
The damage that this pod disease has caused in 
Ceylon I cannot yet say, but where I have observed it, 
it has probably produced a loss of 15 to 20 per cent 
of the annual crop by attacking pods that were 
approaching maturity, and if the number of young 
pods killed and never picked were included in this 
estimate the figure would be much higher. This per- 
centage is for the whole year; daring the wet season 
—favouring the growth of the fungus— more like 
60 per cent of the crop was destioyed or rendered 
of niuch inferior value 
A microscopic examination of the discoloured tissue 
showed the quantities of mycelium, which was larger 
and of a different character from the mycelium in 
the stem, and a portion of it was placed under 
observation in a culture apparatus. After a few days 
the mvcelium began to produce branches at the end of 
which 'egg shaped bodies are borne. These egg-shaped 
bodies are seen to contain circular bodies, and are no 
doubt the sporangia or fruits of a fungus which be- 
long to a group of plants, the greater number of 
which are parasites in the tissues of flowering 
plants and to which the well-known Potato disease 
belongs. 
A few days later I was able to confirm these obser- 
vations by collecting from a pod in the field these 
same reproductive organs on the surface of the pod. 
The fruit of this fungus can be easily recognised by 
the naked eye as a white mould occurring chiefly in 
the farrows of the pod. The r.rpidity with which the 
fungus completely permeates the comparatively soft 
tissue of the pod is shown by the experiments recorded 
later, and an important economic factor in dealing 
with this evil is that, after the pod his been well 
attacked by this fungus, no further nutri'ion reaches 
the seeds and they are found to undergo no increase 
in size. In the case of the younger pods where the 
seeds are still touching the h^uk, the fungus spreads 
into and destroys them, hut if the pods have ap- 
proached to that point of ripenoss when the 
seeds are free from the sides of the pod then 
the mycelium of the fungus does not cross 
the space and the seeds are untouched. 
Having thus examined the whole tree and come 
to the conclusion that the stem was the seat of 
the disease causing the death of the trees, I beg-sa 
to watch carefully for any outward sign of a fungus 
which was causing the canker, but for some time 
without success. I also carried on many cuUures of 
diseased bark in the hope that I might get the 
fructifications under these artificial conditions. All 
these cultures, however, fed a prey to the enemies 
I have mentioned before withoui having produced any 
reproductive organs. 
However, on January 24th I found a white ex- 
crescence on the cankered portion of a Red Cacao 
tree, and on microscopically examining it found it 
to consist of a mass of mycelium bearing oval-shaped 
thin walled bodies which I placed under hourly 
examination in a drop culture. In the course of 
12 to 15 hours these bodies began to push out tube- 
like processes in diameter about a quarter the breadth 
of the oval bodies. 
The processes in some cases grew more than ten 
times the length of the oval body in 18 hours; many 
of them sent out two tube-like processes, in some 
cases, three, and these frequently coalesced so that 
a string of two or more up to six or seven were all 
growing into one tube. _ These tubes grew and 
branched frequently, and after 60 hours produced 
some smaller branches slightly conical in shape, at 
the end of which were a number of spherical bodies, 
which, after a few hours, were seen to consist of 
bodies of the same shape as the oiigiual spores, and 
these in their turn pushed out tube-like processes in 
the same manner as previously described. 
These facts leave no doubt that these oval bodies 
are spores. Spores are the portions of a fungus 
capable of producing a new individual, and they may 
for practical purposes be considered as the seeds of a 
fungus. 
During the few weeks following the discovery 
of these white sporophores on the bark of the 
Cacao, I found them on many trees in different 
parts of the Estate, and collected and examined 
a large amount of material. A fortnight later I 
found a sporophore which contained bodies of a 
different kind to the previous spores. These new 
bodies were about six times as big as the former spores 
and crescent shaped or in the form of a bent cyclinder 
and usually 8 septate — i.e., divided into 8 or less 
compartments. On placing these bodies under con- 
ditions favourable to their development they pushed 
out tubes from one or more of their comp.ariinents, 
and these tubes grew and branched until destroyed 
by bacteria and microscopic animals. In some cases 
in one sporophore I found both these spores recur- 
ring; the smaller oval spores forming the mass of 
the outside of the sporophore and only a few of the 
larger spores occurring. 
As is well known to students of mycology, the fact 
of these two kinds of spores does not necessarily 
