November i, 1890.] THE TROPICAL AGRICULTURIST. 
menta witb both copper and iron salta aa a manurial 
remedy for the same diseaaea, and the fungoid diseases 
of cultivated plants generally, nearly two years ago. 
Mi Girard, however, shows that a solution of sulphate 
of copper used as a preventive of the potato disease is 
not only very eflScacious, but that it results in a gain to 
the crop such aa more than pays for the expenses of the 
treatment. Even when used as a purely curative 
agent, he says the yield of healthy potatoes is increased 
from between twenty to twenty-three per cent. 
It has been found that when leaves, or rather 
plants, are grown in unhealthy situations, such as 
where there is a deficiency of light or nutriment, the 
green chlorophyll becomes degraded in its functions, 
and assumes another colour indicative of this fact. 
The commonest of the degraded colours of leaves is 
some high tone of yellow. This is due to the presence 
in the cells of carrotene, instead of chlorophyll. More- 
over, our orange and deep yellow autumn tints are 
due to the change of the latter into the former. 
Somebody spoke of the present as the “ age of 
iron,” until a recent writer termed it the “ age of 
steel.” But wood is not yet disused, although as 
regards house-building it is no longer an “ age of 
timber,” builders having discovered with how small 
a quantitv of wood a house can be built. But wood 
is not timber, although many people confound the 
two. Tree terns and palm trees have large woody 
stems, but nobody uses them as timber. They would 
rot directly.* The simple structural forms of timber 
are coniferous tree.s, such ns larch, pine, &c. They 
possess the lo sest ti.'-sues, which soonest decompose 
(ia spite of their natuml turpentine), and const queutly 
are much employed under certain conditions. In them 
the woody bundles run the length of the stem, and 
produce “ grain ; ” but we do not find in the structure 
of such timber the horizontal bars of wood we see in a 
section of oak, ash, beech, &o. The real timber trees 
were those used by our fo-efathers in the old-fashioned 
houses, built when real timber was as abundant as 
“ wood,” so they helped themselves to it, as the 
beams and rafters of our old houses prove. The oak 
and ash and other real “ timber trees ” are built up 
naturally into a solid woven fabric, consisting of 
vessels and woody bundles running lengthways of the 
trees, whilst such extra additions as the “medullary 
rays” (absent in cone-bearing trees) are interwoven 
into them from the core to the bark. Generally they 
increase at the rate of one added ring of growth per 
annum, but this i.s not necessardy so, especially in 
young “ timber trees,” in which the rings repre ent 
merely a fresh spurt of growth, annual or otherwise 
The seasons are now known to exercise a wonderful 
influence uiton the nature of the rings of woody growth 
added in the older timber trees annually. We have 
dry summers and wet ones. Nobody can prophesy 
(until afterwards) which will be the ca.se. It is ouly 
in summer, when the leaves are crowding the trees, 
that the timber of the woody trunk can grow 
exogenously. Therefore it i.s evident the nature of 
that growth must largely depend on the character of 
the s-ason. One ■ f the worst things which can happen 
to wood (considered as “ timber ”) is when there has 
been a succession of dry seasons followed by wet 
ones. During the latter the tree forms what is known 
as ‘‘weak wood” — so weak, that not unfrequently, as 
the growth progresses outwardly, it is detached at 
the weakpaDof the ring from the previous growths. 
Tt'is is l(chnitally known as a “ring-shake.” Coni- 
ferous t' ees can gC'^w on scanty soils. They are the 
oldest tiees in the world, giologioally speaking, and 
are used to the poor soils of a primeval world. Oaks, 
beeches, ashes, &c., ive among the latest introduced 
of tree. Th'y cauuot live on a ve -etabte pauper 
diet, but require the rich subsoils of the latest 
geological fonnation.s — clay, marl &o. 
* Dr. Taylor had in view the general run of jjalms. 
There is no better timber for i aliens and reepers 
of lioucC roofs than that of the palmyra palm, while 
selected coconut trees are good for similar purposes, 
— Eti. T.A. 
It is a well-known fact that the more we cultivate 
any particular crop the greater is the number of dis. 
eases to which the latter becomes liabl'-. is it due 
to overcrowding — to increasin? the individual plants 
we denominate a ‘'crop”? The potato disease was 
hardly known until Imlanl scarcely grew anything 
else but potatoes. Vine diseases (animal and vege- 
table) have accumulated with extended vineyard plan- 
ting. It is the same with orchards, olive. yards, orange- 
groves, &c. The cullivii'iou of oranges all over the 
warm temperate parts of the world has mightily in- 
creased within the Is^^t few years. P -ople have 
learned to lore Ihein, and increased trans t has brought 
the producer and consumer nearer toge‘ her. Oranges 
»re no longer fhe so'e luxury of the rich, and the 
objects of envious desire to the sick poor. But 
with increased cultivation have come iiicrea.sed dis- 
eases to the fruit. They are attacked by blue and 
gi ern moulds, which destroy nearly half the quantity 
that arrives in Great Hr'tain. They are also subject 
to extensive ravages by ,a peculiar species of email 
fly, whose pupa-cases may be seen embedded in the 
outer skin of most oranges by thousands, looking 
like so many carraway seeds. The name of this mi- 
nute insect is Cersditis citnpurda. Recently another 
entomological enemy to the orange tree has been 
discoverfd in the larva of a he 't^o (Ceravihi/x ineles), 
which bores into the lower jiart of the stem and 
down into the roots. This g ub seems to be either 
identical with, or nearly allied to, the Cossus of 
the anoieot Romans A. species of Praya has also 
this year been found feeding iu the buds of orange 
and lemon tree.s in the south of Europe. Let Aus- 
traliau orange-growers, therefore be. on the look-out 
for this new arrival of enemies. 
Microscopy has done a g- od deal for practical and 
technical science, and it promises to do a good deal 
more iu the future. Au interesting paper has just 
been read before the Trench Photographic Society on 
microscopic sections of wood. The French Inspector 
of Forests pointed out that such photographs permit 
the trees which furnish the woods to be classified, 
owing to the microscope bringing out the structure 
of the cells and fibres, so that thin cuttings of any 
wood can be compared with standard photographs 
so as to enable them to be identified at once. 
Messieurs Gayon and Uubourg have been exploring the 
mysteries connected with the important subject of the 
alcoholic fermentation of inver ed sugar, and have laid 
the results before tne French Academy of Sciences. In 
brief, the following are the conclusions they arrived at. 
They followed the progress of the fermentation by means 
of the polariraeter, a'.d they prove that the two com- 
ponents of invert sugar are attacked with different de- 
grees of rapidity, and that d fferent ferments do not act 
in the same manner; some attack the Iievulose by 
preference, and others the remaining compouen 
At the risk of repeating what you may have already 
heard of, I do not hesitate to give the following 
important bit of news connected with the banana 
plantations. The discovery was made accidentally in 
Fiji — the paradise for Australian bananas. There can 
be little doubt the discovery will prove valuable in all 
tropical countries where bananas are cultivated. 
The banana disease had broken out virulently on 
a plantation at Vaniia Levu. Near the seasliore a 
banana patch was very muoh di.seaaed. Some time 
ago the sea broke over into it, the salt water remain- 
ing there for about an hour. All the plants were 
killed as far as the standing stems were concerned ; 
but vigorous young shoots oame up freely from the 
roots, and were not ouly quite free from disease, but 
soon began to bear much larger bunches of fruit than 
the parent plaii‘s ever did. The planters noticed 
this effect, and immediately tried an experiment 
upon a iminhor of diseased bananas which the water 
had not reach' d . They cut down the diseased plants, 
stirred the ground about them, and then poured three 
or four buckets ot sea water about each plant. The 
parent stems withered, but vigorous young shoots 
sprouted in tlieir place without a sign of disease. 
The question of a scientific investigation into the 
aeration of soi's must commend itself to .dl agricnl- 
