Oct. 1, 1898.] Supplement to the ''Tropical Agriculturists 
299 
merely a table or chair leg, the stiffness of wood 
is an essential qarility, and in many if not most 
ca.'ies it is far more important tlian the ultimate 
strength. Thus a rafter or joist r.eod not be 
very strung, but it mu^t bend but little under it;s 
as.signed load, and even in furidture an.d smaller 
objects the piece must not only be sufTiciently large 
to hold up its weight without breaking, but to 
hold it without being distorted to an unsightly 
or troublesome degree. In this case ultimate 
strength is not considered, but stiffness or elasticity 
rather, and in the majority of cases a " strong- 
wood " is, with tlie artisan, really a stiff wood. 
The stiffnc-s of a piece of wood depends on its 
weight and its structure. Single tibres of different 
woods niny be found to be alike in stiffness, strength 
and degree of extensibility, both being practically 
alike chemically and physically, and yet there may 
be a great difference between the two woods. Tiiis 
diffei'ence must therefore be in the combinations 
in which the fibres occur in the wood structure, 
whicii is a ready and plausible explanation for 
such differences. 
For instance, to contrast a typical hard wood 
■witli a coniferous wood; we find 
1. The elements of structure are alike in coni- 
fers, unlike in hard wood. 
2. Tliey are all large (comparatively) in coni- 
fers, while in hard wood extremely small elemenis 
(fibres proper) form scattered bodies among larger 
ones (jjarmcliyma) and very large ones (the vessels). 
3. These bodies of small fibres, tlie stronge-t 
part of the wood, have extremely thick walls, 
compared to their size, in the hard woods, but 
much less so in the conifers. 
4. The fibres in conifers are arranged in per- 
fect rows (or really sheets, for the cells of each 
row are priicticallj' conterminous), those of hard 
woods are found in divided bodies, and ajjpear 
like separate strands of specially strong materials. 
In addition, tlie fibres, (traclieids) in conifers are 
usiuilly much hmger ihan those in hard woods. 
On account of these structural con^ i ions the 
fibres in the conifers net much more peifectly 
together and albw less "give" than the 
heterogeneous elemdits, and espeeiilly the 
separated strands of fibres in liaid woods, 
which arrangement permits more " give, " and 
tills "give" lessens the .'stiffness or elasticity of 
tiie hard wood, b'or if we le urn to our sing'e 
cells we would have the ujiper part com- 
pressed when the fibre is bent, the lower ex- 
tended, and the behaviour would simply depend on 
the shape of the fibre and the material of 
its wall, but if we have a set of fibres and vessels 
grown together and tested, the behaviour 
depends not only on their sliape and the 
materia], but also on the relative posilion of the 
fibres and other elements. Those which are crooked 
or oblique on the upper side of the stick will have 
their unf:ivoural)le attitude increased, those on 
the lower side will merely be straightened or but 
paitly strained, while the main part of the load 
applied at first is borne by only a part of the fibres, 
that is, tiiose stniightest in their position. Here 
the large fibres of the conifer with their regularity 
of arrangement all fall in line at one, they are 
"staiglit grain," the "give" is small, and the 
timber is stiff, Moreover, when tlu load is 
j-enioved the case is exactly reversed. The fibres 
of coniferous wood, all being strained, exert 
the same power to return, while many OJ the 
fibres in the hard wood, on the other hand, are 
really under but little strain, they make little 
effort to return, the timber does not " spring 
back," and thus is neither very stiff nor springy 
or resilient; it is not very elastic. Thus 
it is that conifers are, as far is known at 
present, generally stift'er clian hard woods of the 
same weight, the difference of en being very 
considerable. The finer and Ih. more even the 
structure of the hard wood, tl:f straighter the 
grain, the greater the weigh! of any wood, 
and the more perfectly it is seasoned, the stlffer 
it is. In conifers this quality seems to vary 
directly with their weight. In hard woods the 
matter is too little known to warrant any general 
statement, though here, tco, heavy woods like 
oak and ash are stiffer than light woods, such 
as poplar, 
A DrSE.\SE 01'' THE PL.\.\TAL\ TREE. 
We find in the Keiv Bulletin of August, 1894, the 
followingremarksreferringtoplantains :— "Taking 
into consideration the immense area over which 
these plants have been cultivated, the lengthened 
period during which they have been subject to 
the control of man, it is remarkable that no 
chronic disease has manifested itself among them 
except m one or two 1 :caliiies." 
In Ceylon, so far as we are aware, no atten- 
tion has been drawn to any form of disease of 
the phmtain tree, but we have heard of such 
in Fiji, and the following is a reference to it :— 
A short account of the disease affecting banana 
plants in Fiji was published in the Knu Bulletin 
December Ib'JO, p. 272. Specimens of stools were' 
received at Kew List year, but the results of an 
investigation of them were purely negative. Mr 
Arthur E. Shipley, F.L.S., to whom they were 
submitted, was unable to detect anything abnormal 
in the roots, stems, and leaves. There appeared 
to be no trace in the specimens, as received in 
this country, of nematode worms, of insects, or 
of any fungoid pe-t. As indicated in the letter 
addressed by this establishment to the Colonial 
Office, dated 13th November, 1890, Sir Ferdinand 
Von Mueller, adopting the view that the disen.-^e 
was possibly produced by a nematode worm, 
recommended, failing success with various in- 
secticides, ploughing the land, leaving it fallow, 
and alternating some other crop. The ground 
could then be re-planted with banana "stools" 
from an unaffected locality. 
The view that the disease was caused, in part 
at least, by nemarode worm-!, is apparently con- 
firmed by an investigation with fre.-h material 
undertaken by iMr. N. A. Cobb, at Sydn^v, New 
South Wales. The results are published "in tho 
Agricultural Gazette of }\ew South Wales, October, 
1831, p. 622. The Fiji plants were found to be 
affected with aphides, wliicli, however, could not 
be proved to have done much damage. In tha 
root-stock a fungus was found, and the fact tlnit 
this does some damage has been established. The 
prusence was sliown by a brown discolonratiou 
of the interior of the root-stock and roots, 
