526 
THE TROPICAL AGRICULTURIST. [December i, 1881. 
B- 
The following table summarizes in a similar way 
the results of the observations made to determine 
(1) how long a time is occupied by the coffee plant 
in forming a complete pair of leaves, (2) at what 
period they become attacked by the fungus, and (3) 
how long they survive the ravages of the pest. In 
all the specimens selected, there were several of the 
disease spots on each leaf ; but, of course, no absolute 
standard of the damage done is given, and it must 
be remembered that a young leaf badly spotted falls 
eeoner than one affected in a less virulent degree. 
The following example will illustrate the mode of 
reading the columns. Taking the specimen F, the 
minute terminal bud evident so early as September 
6th, 1880, remained quiescent during forty days — 
till October 16th — and then commenced to swell and 
unfold its pair of leaves. In about a month's time 
(November 15th) the leaves were completely formed 
and in full activity, and apparently clean and healthy. 
November 13th was the last date on which no trace 
of disease was visible to the naked eye ; but it is 
evident, from what is known of the periods in the 
life-history of HemUeia. that the germinal tubes had 
already entered the stomata, and formed mycelia, for 
on November 23rd the yellow spots ("pin-spots") 
were apparent, and had developed spores before De- 
cember 5th. The formation of spores continued, and 
the leaf was badly diseased with "rust patches'' 
before December 22ud, when the spots were already 
old and turned brown. On January 1st, 1881, the 
leaf had fallen, and an examination of the last two 
columns shows that, out of 2^ months' term of life, the 
leaf was obviously pestered with the fungus half the 
time. Moreover, we must recollect that nearly a 
month (October 16th to November 15th) was occupied 
in bringing this leaf in full activity, and probably a 
fortnight must be added to the last column, during 
■which time the mycelium was forming. How little of 
the total life and powers of such a leaf benefited the 
tree will be evident on comparing these results. 
The method adopted in arriving at these conclu- 
sions was to mark a given vigorous twig, and note 
the progress of the bud, fungus. &c., at intervals of 
a few days. No other conclusions than those for which 
the tables are designed are intended to be drawn : 
eg., in the example given, the date December 5th (in 
the 6th column) does not mean that the first spore 
formed on that day ; but that, taking notes of the 
progress of events on December 5th, I found spores 
were already formed by the spots in some quantity ^ 
whereas they were not present when notes were taken 
some days earlier. 
To take another example (K), we find a very differ- 
ent series of events when no mycelium or only an 
odd spot appears : here the bud of January 30th 
began to unfold in February, and reached its full 
development as a pair of leaves about March 10th. 
Up to June 26th no signs of disease had appeared 
and we notice that the traces of spots noted on July 
6th never came to anything, as signilied by "0" in 
the column : the leaf fell on August 10th, after a 
total life of 21 weeks or so. In such a case, we may 
safely assume that its work was chiefly devoted to the 
benefit of the tree : — 
Time 
during 
which the 
" disease" 
was visible 
( approxim- 
ate). 
eoOMOoaiiooooo 
Total 
life of 
unfolded 
leaf (ap- 
proximate). 
Date on 
which the 
leaf fell. 
Dec. 22 
20 
30 
Jan. 1 
June 29 
Aug. 3 
July 6 
Aug. 10 
o-» S a 
fill 1 
Dec. 1 
Dec. 5 
Dec. 22 
22 
22 
0 
July 15 
0 
0 
Date on 
which the 
leaf was 
"rusted." 
Nov. 18 
Dec. 5 
Nov. 23 
30 
Dec. 5 
22 
0 
June 20 
0 
0 
Date on 
which the 
spores 
were first 
noticed. 
cs co t- oo oo io m 
. o o o 
oz, - - *q S 
Date on 
which the 
"pin- 
spots" 
were first 
noticed. 
Oct. 20 
Nov. 1 
Nov. 16 
1 
23 
Mar. 29 
May 8 
0 
July 6 
Last date 
on which 
leaves 
appeared 
quite 
clean. 
Oct. 16 
29 
Sept. 30 
Nov. 15 
Oct. 29 
Nov. 18 
Mar. 14 
April 25 
May 8 
June 26 
i 
Date on 
which 
leaves 
may he 
considered 
adult. 
Sep. 30 
30 
30 
Nov. 15 
Oct. 16 
Nov. 15 
Feb. 27 
27 
Mar. 14 
Mar. 10 
Date on 
which 
unfolding 
of leaves 
had 
begun. 
Aug. 30 
30 
Sep. 17 
Oct. 20 
Aug. 26 
Oct. 16 
Feb. 1 
1 
10 
ii 5 
Date on 
which the 
bud was first 
noticed. 
t-CS-^OOOCiOO© • 
WNHCOIN IMCOCOCO 
<i eq o p h h M m k 
c. 
An instructive series of observations were made to 
obtain an answer to the question : how long will the 
leaf remain on the tree when not attacked by Hemileia, 
or when only one or two small and barren disease 
spots appear ? The methods adopted were the same 
as before. 
To tike an example (C) we find that, on December 
20th, the leaf was adult, and in full working order. 
It retained its green, bright colour until April 2nd, 
when a few laint yellowish cloudy patches were 
observable. (These are the signs of approaching dis- 
solution.) 
On April 25th the leaf had become yellow, like 
