December i, 1881.] THE TROPICAL 
AGRICULTURIST. 
495 
exceptional ones, and no reliance should be placed in 
them an fair indications of the value of puhe.sctm bark. 
The ordinary yield of quinine that may be confidently 
expected is from '?'50 to 3 '50 per cent. Renewal of 
the bark is effected with great facility, tlie resulting 
yield of quinine being from 3-10 to 4 !)0 per cent. In 
this, and in the large yield of thick bark, lies the ad- 
vantage of cultivating this trees which i3 greatly in- 
creased by a careful selection of stock trees. 1 have found 
the seed of this hybrid very hardy and easy of 
germination, the young plants growing with the greatest 
rapidity and should most strongly recommend its fur- 
ther cultivation, by cuttings, if possible. The eleva- 
tion at which pvbescens grows is about the same as 
that for nuccirubra, and probably extends higher." 
Mr. Mclvor may have been wrong in regarding his 
Pubescens as a hybrid, indeed we are likely to have 
the term discarded— but Howard's analyses cannot be 
wrong. There is another C. pubescens, Vahl. (Arica 
bark) less well-known. — Ed.] 
SILK-GROWING IN CEYLON. 
Parate, Moratuwa, 15th Oct. 1SS1. 
Sir, — With reference to your remarks on "Silk Grow- 
ing in L'eylon " in your impression of the 7ih, Dr. 
Vanderstraaten seems to have misunderstood what I 
told him about the domestication of the tussur silk- 
worm. I said that I had not succeeded in rearing 
the tussur silkworm on growing trees in the open 
air, because the caterpillars wen: always devoured by 
birds, lizards, or ants ; but I did not say that I he 
tussur silkworm could not be domesticated. The 
nature of this insect renders it unsuitable for feeding 
on plucked leaves like tbe mulberry and castoroil 
tree silk- worms, but it cau be kept on cut branches 
with their ends inserted in water to prevent the 
withering of the leaves, and I now have about three 
hundred tussur silkworms and about as many of tbe 
atlas kiud which I am keening in that way for the 
purpose of sending the live chrysalides to Loudon for 
trial in England by Mr. Alfred Wailly ( Mcmbre 
dc la SocMU d' Acclimatation de France). The eggs of 
both species hatch too scon for transmission from this 
to England. I believe that any effectual method of 
protecting the silkworms from tbe numerous 
enemies to which th'ey would in this country be 
exposed, if they were on growing trees in the 
open air, would be more troublesome and expensive 
than the culture of the mulberry tree and domestic 
management of the true silkworm. But by my plan 
of keeping the silkworms on cut branches or suckers 
inserted in water-pipes, it would be quite practicable 
to produce cocoons in sufficient quantity for manufactur- 
ing purposes, and I shall be glad to show it to 
brobody taking an interest in the matter, Bycoppie- 
the most suitable tree to cultivate for the purpose, 
nit that could bo easily nsertained by enquiry in the 
districts in which tussur cocoons arc collected for manu- 
facture. 
Though a species of bombyx may bo polyphagous 
in a stito of naturo, yot it clues not follow that it 
has not got its ow n proper food plant on which it is 
more at home thin on any other. The atlas, for 
instance, is very polyphagous, and yet I know of no 
tree oxcept tho liilnta Soxburghiana, on which the 
COOoonsor larva- are to bo found in large numbers, nor 
have I successfully domesticated i he atlas moth on any 
olhor tree for more than one generation, though I 
have tried several other trees. There does not »ecm 
to be in this country any tree on which tussur cocoons or 
ttrvn are to bo found in greater numbers than twos 
and threes, but in the north of India there must be 
trees of one or more species on which the insect is 
to be found in much greater abundance, because the 
cocoons could not otherwise be collected in sufficient 
quantity for manufacturing purposes. The tussur silk- 
worm has not hitherto been artificially reared, all the 
tussur silk in use being obtained from wild cocoons 
gathered in the jungles ; and before attempting the 
domestication of this kind of silkworm as a com- 
mercial speculation, the species of tree on which it is 
found in the greatest abundance in a state of nature 
should be ascertained. 
The subject seems to be, commercially speaking, 
better worth investigating than some of the " new 
products " that we read of ; but it must not be 
supposed that tussur silkworm can be used as 
a substitute for true silk which is the produce of 
tbe Bombyx won or Sericaria mori as it is now named, 
and in a country where mulberry leaves can be ob- 
tained at all seasons, it would, in the absei'ce of 
epidemic disease affecting the true silkworm, be of 
no practical use to cultivate plnnts for feeding the 
tussur species, unless it were for the purpose of utiliz- 
ing soil too sti rile for the growth of the mulberry 
tree. I am using a common patana weed, and it 
answers better than any other plant that I have 
tried for feeding the tussur. 
There is no doubt about the suitableness of this 
country for tbe Sericaria mori or true silkworm, if 
the business be managed in a rational way ; but no 
success is to be expected from attempts to feed the 
silkworm on the leaves of the lettuce tree or any- 
thing else but the mulberry leaf. Very many attempis 
have been made to find substitutes for the mulberry 
tree for feeding the silkworm, aud success has from 
time to time been reported, but the only useful result of 
all such experiments has been to confirm practical 
sericulturists in the belief that no substitute for the 
mulberry tree can ever be found. In countries where 
silk production is an established business it is not 
necessary that the sericulcurist should be a mulberry 
planter, because mulberry leaves can be bought in 
any quantity required, but here it is of no use to 
begin with silkworms without first making a mulberry 
plantation. It is also useless to send all the way to 
"hina aud Japan for silkworm eggs, at the risk of 
being cheated with bad ones, when eggs of warranted 
good quality can be had by application to Rev. Father 
Palla of Galle. 
Three species of mulberry have already been natur- 
alized in this country — the common sort {Mortis indica), 
the white mulberry (M. alba), and the large-leafed 
Philippine Island species (M. vndticaulis). I find the 
Inst mentioned the best for this climate, but, per- 
haps, the white might be the best kind for the colder 
parts of the country. The commou mulberry does 
very well if it is constantly pruned so as to make 
it produce tender shoots, but the leaves become rusty 
aud unfit for use if they are not plucked from the 
tree soon after their appearance.— Yours faithfully, 
ALUX. T. GEDDES. 
A CURE FOR GRUB. 
lfith October 1881. 
Dear Sir, — Will your correspondent, whose opiuion 
you gave as a footnote to " Moles "'s letter iu your 
issue of the 1 1th, kindly give us his reasons for 
adopting the Government principle of <y/'i>Ai ho/; 
moverr ? Though I have not collected so many as 
two million cockchafers, I have seen enough of the 
ravages of grub to convince mo that planters unaided 
will be unable to apply a remedy, aud until tho grub 
pest is overcome tho disastrous effects of leaf-disease 
will bo more aud more apparent iu tho table of 
exports.— Yours faithfully, AUSPBX. 
