December i, 1881.] 
THE TROPICAL AGRICULTURIST. 
525 
escape the action of even the most efficacious 
remedies, that no good and lasting results can 
be obtained from external applications unless the 
sources of reinfection be removed. No attempts to 
combat the disease by passing ingredients into the 
tree have shown any trace of success : the mycelium 
cannot be attacked after it has entered the leaf. 
7. — Diseased leaves should be collected and destroyed, 
and every means possible employed to prevent the ingress 
of winds. Cultivation should be directed to these end*, 
and the pruning and manuring, as far as possible, ar- 
ranged so that large masses of young foliage are as 
seldom as possible exposed as a surface of food mat- 
erial for tho spores at those times when they are 
most blown about, as at the bursts of the monsoons. 
In cases where tho disease is threatening to denude 
the trees of leaves at the critical period wlvn crop 
is ripening up, there can be little question of the use oj 
lime, unless weightier considerations, based on the 
results of experience with that particular soil, forbid it. 
8. — Manure can in no sense be properly looked 
upon a* n cure for the disease. In so far as it enables 
a tree to clothe itself with dense foliage, the tree 
may be able to afford the sacrifice of a number of its 
leaves to the fungus ; but the well-fed mycelium will 
in such cases produce more spores in proportion, and 
these may be the more readily distributed, and germ- 
inate on other leaves, and so tho stock of fungus 
bo actually increased. Nevertheless, careful manuring 
is necessary for the production of crop without 
d image to the tree. 
9. — Tho burning of fallen leaves, &c, is almost 
universally condemned by planters as too dangerous. 
In cases where this cannot be done, it is better to 
bury the l-avos 
tossing about. ! 
and primings ( 
should be caret 
earth and not 
suggestion that 
pigs and cattle 
even this plan i 
be blown about 
are gathered aft 
stroyed with the 
of it* having arise 
of the jungle, that this view 
probable. Once on the cofl 
very rapid, where such larg 
No traee of valid evidence 
the disease has been "indue 
or "caused by alterations 
it is, beyond all doubt, the 
a fungus dt rived from with 
were cither imported into 
event) or came from the ua 
In conclusion, I beg to c: 
ain important d t ails in 
remain, Sec, 11. MARSHAL! 
Peradeniya, September 1881. 
d primings than to leave them 
loing this, the layers of leaves 
h may be mixed with weeds) 
covered with caustic lime and 
irbcd for several months. The 
leaves might be placed under 
ds a less safe alternative ; but 
neb better than leaving them to 
estates. The sooner the leaves 
ailing, the more spore? are de- 
leaf-disc ise cannot be traced with 
evidence is so strong in favour 
■A for the views that 
y artilicial manuring," 
10 sap of the tree ;" 
ilts of the action of 
the spores of which 
Ion (an improbable 
nir attention to cert- 
following appendix. I 
A1!D, B.A , Camb., 
Cryptoganiist. 
A P P 10 NDl X. 
Tho following table summarizes shortly a number 
of experiments, selected from a large series, made to 
determine (1) the timo occupied in the germin ition of 
a ipore, (2) how soon afterwards the ' disease spot" 
appears on the leaf, (."!) how long the mycelium may 
continue to produce spores. In uach caso a vigorous 
young plant was seh cti d, which hud been grown for 
•Otnu months in a sheltered situation, nnd was clean 
and healthy. On a recently formed leaf a sowing of 
132 
spores was made, kept moist for 24 to 48 hours, and 
then (the damp cell having been removed) placed 
in a carefully cleaned Wardian case, well lighted, 
sheltered, and kept at an average temperature of about 
78° Far. In all cases the spores were found to germ- 
inate in 24 hours, and the tubes had commenced 
to block up the stomata within 48 hours. For all 
examples, also, the following holds good : the " dis- 
ease-spots" appeared on the leal' on which the sowing 
was made, and within the area of sowing, and no- 
where else on the plant. Moreover, no more "disease" 
appeared on the same plant, even after keeping it for 
several (six or eight) months, unless a fresh sowing 
was made and kept moist for 24 to 48 hours a before. 
These facts prove (1) that the "disease-spots" and 
"rust" result from the tub s and mycelium traced 
by the microscope from the spore, (2) that tho fundus 
corresponds in area with the disease spo 1 , (3) that, 
even if spores be present on the loaf, no "disease" 
results, unless the conditions (moisture, &c.,) for germ- 
ination be also present. Finally, taken in conjunc- 
tion with the results of microscopic analysis, they 
prove that the disease-spot is due to the action of an 
organism derived from without, which passes through 
definite changes, and has a limited term of life : — 
lis 
.a to &£, 
il! 
Time 
dming 
which 
spores 
were con- 
tinuously 
produced. 
10 weeks 
8 weeks 
7 weeks 
7 weeks 
11 weeks 
10 weeks 
<c _ HP w r 
Tim 
occupiec 
formii 
" disea 
spot. 
CO -SS -H <N O-l O CO U3 Tfj CO CO J^j 
Approxim- 
ate date 
on which 
spores 
ceased to 
form. 
May 1 
April 1 
Mar. 31 
April 1 
May 1 
April 20 
Approxim- 
ate date 
on which 
spot turned 
black 
in centre. 
April 25 
Mai-. 14 
Mar. 10 
Mar. 12 
April 2 
Mar. 30 
Mar. 20 
Approxim- 
ate date 
of greatest 
vigour. 
h ,0° jq -a ^ is ^ ' 1 
& 3 1< & a < 
Date on 
which 
spores were 
first seen. 
oistooooaooono 
rH Ol CO i-S Ol 
44 i4444 i i c %°44 
Date on 
which spot 
appeared. 
■ateoirj.tfcoOTftec-t-cocQ 
ih in e* <-> 
,0.0 a -a -a j a sc sjb.a 
Date on 
which 
spores were 
sown. 
Jan. 27 
Jan. 30 
Jan. 11 
Jan. 23 
Jan. 22 
Jan. 18 
Jan. 22 
Jan. 11 
July 24 
Aug. 1 
Jan. 21 
Jan. 20 j 
1 
0 
O 
0 
■fi 
a 
> 
A. — Jamaica 
B. — do ..I 
C. — Nukuuuad 
D. — do. 
E. — do. 
P. — Java 
G. — do. 
H. — Imlian 
I. — Ceylon 
K. — Java 
L. — Ceylon 
M. — do 
1*1 
p 0 ft 
S * — 
J J 3 
-3 = a 2* 
6 — I a 
S a -a 
S2K 
I .3 
