m THE TROPICAL 
presence of manganese, which M. Bartrand regards 
as the vehicle of the oxygen, was noticed in all 
the matters at the author's disposal. 
The above observations led to the belief that the 
oxydases confcainsd in the fruit of the vanilla mmt 
play an important pirt in the preparation of the 
essence itself ; but an apparently serious objection 
may be opposed to this supposition. In the method 
of preparation now adopted at Li Reunion, the 
first operation to which the fruit is subjected con- 
sists in immersing it for about twenty seconds in 
water kept at the temperature of 80 to 85 degrees 
Centigrade. Now at this temperature the oxydases 
might be supposed to lose their chiracteristic property 
but experiments, repeated several times, showed 
that the interior of the fruit, immersed in boiling 
water for thirty seconds, did not acquire, after 
such immersion, a temperature higher than 55 degrees 
Centigrade. Now, in practice, whole biskatsful 
of the fruit are immersed in hot water, which does 
not attain boiling point, but at most 85 degrees 
Centigrade while the immersion only lasts for twenty 
instead of thirty seconds. It may therefore be con- 
cluded that the temperature inside the fruit never 
attain 50 degrees Centigrade, and that under these 
conditions, not only is the oxydase not altered 
but that on the contrary the temperature it 
acquires is that which is very favourable to preser- 
vation of the essential properties. 
There remained to determine the nature of the 
substances capable of being transformed into vanilla, 
under the influence of the oxidising agent. Following 
up this investigation, Mr. Lecomte found that the 
juice extracted from the vanilla plant contains 
another ferment possessing the property of hydra- 
tizing the starch and which, acting on a solution of 
conif'erine, promotes the formation of a substances 
possessing the same reactions as that the constant 
presence of which was noticed in the tis ues of the 
vanilla plant. The simultaneous presence of two 
distinct ferments, one hydvatizing and the other 
oxidising, the existence of which appears intimately 
connected with the production of \anilliue was, there- 
fore, noticed in the vanilla plant. 
In fact, having selected two similar specimens, 
A and B, of ripe fruit, forwarded in spirit from 
La Reunion, the author proceeded to prepare them 
by boiling. Specimen A was first raised to a tem- 
perature of 100 degrees Centigrade for ten minutes, 
while B was not subjected to this operation, the 
two specimens being otherwise prepared in the same 
manner and in the same space of time. Specimen 
A became soft, and only g^ve out a scarcely per- 
ceptible odour of vanilla ; but B on the contrary 
assumed the characteristic odour of vanilla, while 
having become partially covered, after a few days, 
with small crystals, which were easily recognised as 
those of vanilline. 
By way of conclusion, the following hypothesis may 
be ventured as to the formition of vanilline in the 
fruit during its preparation : — The hydratizing ferment 
may be supposed to transfjrmthe nascent coniferine 
into coniferylic alcohol and glucose, the presence 
of which latter substance is indeed constant in 
vanilla ; and moreover, the coniferylic alcohol is 
probably transformed into vanilline by the action 
of the oxydase. — Journal of the Societv of Arts. 
THE CACAO FUNGUS. 
Bl Albert Howard, s.A.i a.r.c.s., f.l.s., 
Mycologist to the Imperial Department of Agriculture 
for the West Indies, late Scholar of St. John's 
CiUec/e, Cambridge. 
The Pangua 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 
ftbove oa the 8ugar«3ane» la the case of the poda the 
AGRICULTURIST. [Dec. 1, 1902, 
pycnidia are often formsd singly just under the epider- 
mis, and the latter is ruptured by the growth of these 
structures. In diseased branches, or on the trunk of 
thi tree, the pycnidia occur nsuiUy in colonies just 
u ider the bark. The appearance of a branch attacked 
by the Fungus, which has been kept in a moist cham- 
ber a short time, is shown in Fig. 10, and a transverse 
section through one of the colonies is given in 
Fig 11. 
Some general indication of the appoaranoe of cacao 
trees and po3s apparently attacked by this Fungus 
may be of interest. It is quite coinmou in Grenada to 
see ca ao trees dying bxck to a slight extent at the 
extremities of the branches, a phenomenon probxbly 
duito poverty of soil, wind, drought, or defective root- 
action, or perhaps to a combination of these causes. 
Iq all such cases there is ,i sharp linfl of demiroation 
between the dead and living tissuss, and although 
several Ascomycetes are to be found in the detd 
wjod, they appear to be purely saprophytic in charac- 
ter. In miny cxses, however, dying bxck goes on to a 
very greit extent, extenling to the larger branches 
and the trunk, and, in spite of the production of 
suckers at the base, the trees are often killed out- 
right. In sujh cases there is no boundary line bstween 
dead and living tissues, but an intermediate zme, 
often as much as two feet in length, always oicuis bet- 
ween the obviously dead and living tissue. Mycelium 
can be easily detected in the young wood in this transi- 
tion region, and the pycnidia referred to a'jove are to be 
found under the birk. 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 siprophytic origin of the Fungus 
The mycelium mikes its way in the wood from ele- 
ment to element by means of the pits in the walls of 
the vessels and cells, and where the hyphae have com- 
menced to darken in colour this point can be deter- 
mine i without staining (Fig. 12). 
In oases where pods are apparently attacked by the 
Fungus this is very common near the 'breaking- 
grounds,' where the ' beans ' are extracted by the 
pickers, and where it is the custom to leave the 
empty husks on the ground in heaps. The husks 
speedily become covered with the spores of the Faugu?, 
as this fo ni lives on them as a saprophyte. The 
rind of the pod turns brown and mycelium soon 
spreads to the mucilage surrounding the seeds com- 
pletely destroying the pod and its contents, usually 
in from six to ten days. The diseased areas com- 
mence as a brown spot, as a general rule either at the 
free end of the pod, or in the groove round the inser- 
tion of the stalk, or at the point where the pod come 
in contact with the branch. These plices are those 
which are liable to be moist long after the rest of the 
pod is dry, and indicate the probability that infection 
may here be effected by spores without any previous 
wounding. 
The artificial cultivation of the Fungus wis carried 
out in an exactly simiUr manner to that employed in 
the case of the sugar-cane Fungus described above 
and as far as possible similar cultures of the two forma 
were made and examined at the same time. 
Stages in the germination of the spore are shown 
in Fig. 13. The germtube grows out into a long 
hypha, at first slowly, but afterwards much more 
rapidly, and extensive branching eventually takes 
place. Septation of the hyphae was not noted before 
twenty hours after sowing, ^nd after two days fusions 
of the hyphae were common : about the same time 
the mj-celium commenced to grow down towards the 
water on the floor of the moist chamber, reaching 
it four days after sowing (Fig. 7), When three days 
old the mycelium gradually changed colour, passing 
through various shades from light yellow to olive 
green, and at the same time the hyphal contents 
began to aggregate in certain portions of the 
mycelium, leaving the rest empty. Oil drops also 
made their appearance. The appearance of the 
mycelium, when eight days old, closely resembles 
