December i, 1881.] 
THE TROPICAL AGRICULTURIST. 
507 
diseased areas. That the planting of other trees on 
estates, and among the coffee, is an important aid to 
the same effect will, of course, be apparent. " Leaf- 
disease " appears to affect different estates in different 
decress on account of variations in soil, climate, and 
other physical peculiarities ; but I would draw atten- 
tion to the explanation of this. Careful cultivation 
and natural advantages of soil, climate, &c, enable 
certain estates to stand forth prominently, as though 
" leaf-disease " did not affect them, or only to a slight 
extent; while poor nutrition, the ravages of insects, 
&c, have in other cases their effect as well as "leaf- 
disease. " 
These attendant conditions, though they may com- 
plicate the problem before the individual planter, have, 
of course, however no connection with the origin of 
the parasite which causes "leaf disease." Manure, 
again, can in no way be looked upon as either acause 
of the disease or a cure for it: its proper action is 
that of a food. 
The question whence the fungus originated admits 
of no direct answer. I have, however, placed before 
you a strong array of facts tending to prove that 
Hemileia existed in Ceylon long before ib was dis- 
covered on the cultivated colfee; if, indeed, Hemileia 
vasiatrix proves identical with Hemileia Canthii, there 
can be little room for doubt tbat the former passed 
to the coffee from jungle, as I have long suspected 
to be the truth. 
A review of events during the past year shows that 
the expectations held by planters during tbe earlier 
months of the season have not been fullilled; and it 
must be recorded with regret that the general and 
magnificent blossom which appeared so promising in 
March last have, with few exceptions, given results 
far below what was expected from them. Notwith- 
standing the favourable weather, and the rarity of 
the fungus at the time, a very small proportion of 
the (lowers came to the stage of young fruit; and it 
is to be feared that a much smaller fraction will be- 
come ripe crop. As an illustration of this, I may quote 
the following from the remarks of a correspondent 
in one of the daily papers early in the year : — 
"The prospects of a really good year could not 
have been more perfectly fullilled from the succession 
of fine blossoms that came out; and, apparently, we 
had wheather to set them beautifully. Hope against 
hope has been disappointed ; the greater number of 
these bloosoms came to nothing ; and then at most 
only gave the crop that is now showing, and that, I 
fin, will prove deceptive, although many estates 
have estimated from 25 per cent, to 50 per cent, over 
hut year. The failure of the blossom is a mystery, 
(or, on examining the clusters that have set, and are 
maturing on ouo sido of an eye on a branch, on the 
other tide of the same eye you find blossoms have 
entirely failed— in fact, when fresh blossoms came 
out of the same eye where the clusters were, they 
also failed, while later blossoms on the same branch 
set all right. This cannot be laid down to leaf dis- 
ease, or want of manure." 
It is important to notice, however, that eome es- 
tates hold forth promiso of even largo crops, and that 
th eneral aspect is decidedly better than it was last 
year at a corresponding period. 
Thit this improvement is largely duo to tho more 
favourable season of tho current year, and tho condi- 
tion of tho trees after tho rest of last year, tbero 
ran ho mi doubt : but to this must bo added the equally 
truo statement that careful cultivation and attention 
have had marked effects in enabling trees to set and 
ripen crop to a larger extent than tliey would other- 
wish have done, as is shown by comparing more 
neglected 00 See. 
Sec. I.— The Life-history of Hemileia Vastarix 
on Coffee. 
§ 1. Tho outcome of numerous observations in addi- 
tion to and in continuation of those referred to in 
former reports, shows that tho history of the fungus 
which causes coffee leaf disease may be fairly stated 
thus. 
An orange-coloured papillate spore, or granule of 
"rust," taken from a patch on a diseased leaf and sown 
in a drop of water on the lower surface of a healthy 
coffee leaf, soon germinates — i. e., it absorbs water ana 
oxygen, swells up slightly, and protrudes a delicate, 
thin-walled tube from one or more points of its surf ace. 
This tube is a direct continuation of the spore itself, 
and the granular orange-coloured contents of the latter 
pass along the cavity of the tube as it extends on the 
surface of the leaf. 1 , 
On arriving at the orifice of a stoma or " breathing 
spore," this germinal tube commences to block it up, 
and soon sends a prolongation through the orifice into 
the passages between the loosely arranged cells of the 
interior of the leaf. Once safe inside the leaf, the 
short tube begins to branch in two or three directions, 
each branch absorbing the fluid bathing the leaf cells 
with which it is in contact. 
As these first-formed branches gather strength and 
material, they put forth several other branches which 
rapidly extend into the spaces between the tissues around, 
and in this manner is formed a spreading meshwork or 
■mycelium of short, stumpy, fungal tubes. As growth 
proceeds from the primary tube in all directions around 
the point of entry, the increasing mycelium soon requires 
more food than can he obtained by simply absorbing 
the nutritive fluids bathing the leaf-cells with which the 
branches are closely in contact ; this increased demand 
for food is effectually supplied after a time by the 
sucking organs, or Jiaustoria which become formed by the 
older branches. Each bores through the wall of the 
cell with which it is in contact, and by means of the 
perforated passage obtains as food the contents of the 
leaf-cell. 
As growth proceeds in all directions from the point 
of entrance of the germinal tube — i.e., a stoma — the 
leaf-cells fust attacked and injured are evidently those 
nearest this central point, and the destruction of tissue 
proceeds in a centrifugal manner, pari passu, with the 
spread of the destroying mycelium. 
The injured cells becomo paler in colour as their con- 
tents become altered and destroyed, and thus shine 
through the outer layers of the leaf with a paler hue 
than the remainder of the tissue : the yellowish circular 
spot thus produced is the first indication to the naked 
eye of the damage done to tho leaf — it is the so-called 
"pin-spot." As the destroying mycelhun extends itself 
further into the tissues, its course is marked by dying 
cells, and a circular spreading of the pale disease patch 
is obvious to the outward observer. From the same 
cause the discolouration appears at a later dato on the 
upper surface of the leaf, as the branches extend there. 
When a vigorous, centrifugally spreading mycelium bus 
thus been formed, the older portions at the centre com- 
mence to form spores : these are produced in compact 
groups from the substance of certain processes which 
aro formed by aggregations of branches of tho mycelium 
forced tluough the stomata. The first formed spore- 
groups appear at thoso stomata which lie close around 
tho point of origin of the mycelium, and they aro fol- 
lowed by others successively protruding tlu-ough stomata 
further and further away from this point : thus, the 
production of spore-bearing heads also takes place in a 
centrifugal manner, and successive circles of them be- 
come arranged around those first formed. Kach sporc- 
boaring head is capable of producing largo numbers of 
spores, successively budding forth during tho period of 
activity. 
