Vol. VIII. No. 87. IMPERIAL INSTITUTE JOURNAL. [March, 1902.] 69 
Influence of distance in Planting, — A study of the relation of distance of planting to 
yield and thickness of leaf, was made at the Wisconsin station. Plants were set 20 inches 
apart in rows 31 and 36 inches apart, and at intervals of 24 inches in rows 42 inches apart ; 
close planting was found to increase the yield, and the plants nearest together in the row 
produced a thinner leaf than those further apart; but lessening the distance between the rows 
did not have this effect. A distance of 31 inches between the rows was sufficient for the full 
development of the plants. The surface area of the cured leaves per pound from the closest 
planting was 42 '01 square feet, and from the widest planting 40'86 square feet. 
Other experiments made with a view to ascertain to what extent close planting may be 
advantageously practised, showed that planting 1 foot apart in the row was not too close for 
Wilson Hybrid, the variety grown in this experiment. From these and other experiments it 
was concluded that too close planting interferes with the developement of the leaves, while 
too large spaces between plants tend to produce coarse leaves. The dimensions of Ihe leaf, 
thickness, elasticity, and size of the veins may all be more or less modified by giving the 
plants space or increasing the number in a row. 
Fertiliser Experiments. — The results of experiments at Kentucky indicated that potassium, 
chloride, and sulphate, gave equally good results as fertilisers for tobacco, and that sodium 
nitrate produced a better quality leaf than other forms of nitrogen. 
Tests with complete and incomplete fertiliser applications were also made. A yield of 
1,460 lb. of cured leaf per acre was obtained after an application of 80 lb. of sodium 
nitrate, 80 lb. of dried blood, 160 lb. potassium chloride, and 140 lb. of double superphos- 
phate per acre, whereas by doubling the quantity of fertiliser the yield of leaf was increased 
to 1,620 lbs. 
Fertilisers used on soil in a good state of fertility, were found to increase the yield of 
tobacco considerably, and potassium chloride proved more efficient than the carbonates of 
potassium and magnesium. 
At Calhoun experiments were conducted on red sandy and grey sandy soils, and it was 
shown that potash had little or no effect on the crop, but nitrogen, either in the form of 
sodium nitrate, ammonium sulphate, cotton-seed meal, or dried blood, caused a marked 
increase in the quantity obtained. An application consisting of cotton-seed meal, acid 
phosphate, and sulphate of potassium produced the best quality leaf. 
The effects of different fertilisers on tobacco were studied at the Virginia station. Five 
plots manured with complete fertilisers, all of the same cost per acre, were compared with an 
unmanured plot. Dried blood gave the largest yield and the best financial returns as a 
source of nitrogen. The tobacco grown without fertilisers ripened ten days to two w r eeks 
later than that grown with fertilisers. 
Influence of Time of Harvesting. — These experiments were undertaken at the Wisconsin 
Station to determine whether the tobacco leaf increased in size and thickness, and whether 
the loss in curing diminishes, when the plants are allowed to stand a considerable time after 
topping. 
The results showed that when the plants were permitted to stand 32 days, as against 
others allowed to stand only 18 days, the thickness and dry matter of the leaf tended 
to increase, and the yield has a like tendency, i.e., after curing, a greater weight of the leaf 
was obtained, but the area per pound of leaf was less. 
It was thus possible to vary the commercial grade, and influence the price considerably, 
by harvesting the crop at different stages of maturity. This was one of the methods by 
which the quality of tobacco might be sensibly controlled. 
Effect of Printing Tobacco Plants. — -Priming, which consists in removing the leaves from 
the stalk of the plant as they mature, has a marked effect on the growth and chemical com- 
position of the upper leaves. The removal of the lower leaves causes an increase of growth 
in the upper, and also a higher percentage of nitrogenous matter and nicotine. Priming is 
believed by many practical growers to be the proper method of harvesting the cigar- and 
cigarette-types, for in this way the leaves are uniformly matured and the subsequent product 
is consequently of a more uniform character. The priming of tobacco is more expensive 
than cutting the stalk, as more labour is required, but the improvement in qualUy fully 
warrants this additional cost. 
Experiments in Topping Tobacco were conducted at the Central Experimental Farm 
at Ottawa, Canada, in order to determine how the time of topping, and the number of leaves 
left on the plants, affect the yield. The plants were topped July 20th and 26th and 
August 2nd, and on each date one plot was cut back to nine leaves and another to eleven 
leaves per plant. The larger yields were obtained from the latest topping, and the greater 
number of leaves per plant. The time and manner of topping has a great influence upon the 
character of the leaf produced. As a rule the earlier a plant is topped and the lower it is 
cut, the heavier, richer and darker-coloured the leaves become. This is a decided advantage 
for some crops, but a disadvantage to others. 
Diseases of Tobacco. — The diseases to which most attention has been given manifest 
themselves during the curing process, and are commonly known as “ stem rot ” and “ pole burn ” 
or “ pole sweat.” The latter makes its appearance as small dark spots on the surface of the leaf 
near the veins and midrib, where moisture is most abundant. The disease is supposed to 
be primarily due to a fungoid growth which attacks the leaf on the surface and gives access 
to a bacterial process of decay by disintegrating and partially destroying the leaf tissue. It 
has been ascertained that moisture and temperature have a marked effect on the activity of 
these organisms. Decreasing the amount of moisture lowered their vitality, and a tempera- 
ture up to 70° F. or even 90° F. favoured their development, while a temperature of over 
IOO° or 110° F. and below 35 0 or 40° F. temporarily or permanently checked their vitality. 
From investigations it was concluded that under the atmospheric conditions most 
favourable to the development of “ pole sweat,” the temperature and moisture in the interior 
of a closed barn could be regulated by artificial heat so as to reduce to a minimum the 
liability of tobacco to damage from fungi or other like organisms. 
“ Stem rot ” is a fungoid disease which frequently affects the stems of the plants in the last 
stage of curing. No special experiments were made upon this disease, but as a remedial 
measure it was suggested that when the crop is cured all stems and refuse attacked by stem 
rot be burned before the fungus has matured, and the barn fumigated with sulphur 
immediately after curing, and again before the harvesting of the next season’s crop. 
Experiments in curing Tobacco. — Tobacco goes through certain processes of fermentation 
from the time it is cut until it is ready for the manufacturer. During this time it is said to be 
curing and ageing. After the harvest the leaves are speared upon laths and hung in a barn 
to dry. Artificial heat is often employed for this purpose. Experiments with different 
methods of curing tobacco have been conducted at several experimental stations. At the 
North Carolina station, the ordinary method of cutting down the plant and curing it with the 
leaves on the stalk proved less profitable than curing by the Snow process, in which the 
leaves are cut from the stalk as they ripen, and cured separately. A greater yield was 
obtained with the tobacco cured by tire leaf process and the quality was better. This effect 
is ascribed to harvesting the leaves as they became mature, while, by the stalk process, many 
of the lower leaves were over-ripe, and the upper leaves still green at the time of cutting. It 
was found that the time and temperature required for curing leaves from different parts of the 
plant varied according to their ripeness, and for this reason the leaf-curing proved the most. 
desirable method, as the leaves were all of the same degree of maturity. At Wisconsin it was 
found that the loss of water in curing was about 71 per cent, of the weight of green leaf. 
It is stated that the changes in the colour of the leaf during the curing process were not 
directly due to the loss of moisture, but depended largely upon the degree of ripeness — the 
riper the leaf, the lighter in colour it would be when cured. 
From data obtained in this work it was concluded that tobacco should be cured in as 
moist an atmosphere as possible, without incurring damage from “ pole burn.” A temperature 
within the curing house not exceeding 75 0 F., and a degree of humidity among the plants 
represented by a wet bulb depression of 2 0 , were regarded as suilable conditions. In order to 
maintain these requirements, the plants should be evenly distributed in the curing-house, in 
order to equalise the humidity of the building, and the ventilation should be under perfect 
control, with a provision to regulate the humidity of the air by the use of artificial heat. 
Fermentation of Tobacco. — The fermentation or sweating of tobacco is carried out in several 
ways. To give a general idea of the method of procedure, that followed in Florida may be 
cited. After the tobacco is cured, the leaves are stripped from the stalk and made up into 
hands, i.e. bundles tied together at the base. These hands are either piled on the floor or put 
into bins, and the fermentation allowed to proceed gradually. The temperature of the pile 
gradually rises, until it reaches its maximum, which is sometimes as high as 180 0 F. From 
this point the temperature gradually subsides, and finally attains the normal temperature of 
the room. 
In connection with the changes which take place during the process of fermentation, 
most attention has hitherto been given to the loss in weight of the leaves and to the chemical 
changes which occur. At Connecticut State station the weight and chemical composition 01 
cured and fermented leaves was compared. The loss in the fermentation of upper leaves, 
short seconds, and first wrappers was 97, 127 and 9*1 per cent, respectively. About three- 
fourths of the loss in the short seconds consisted of water, the upper leaves lost almost 
the same proportion in dry matter, and in the first wrappers the loss of dry matter was a little 
less than that of water. 
The nitric acid, ammonia, fibre and starch contents of the leaves were affected very little 
by the process of fermentation, and the chief loss of dry matter was found to have occurred 
in the nicotine, albuminoids, and amide bodies, nitrogen free extract and ether extract. At 
the Pennsylvania station it was found that the loss in fermentation was greater with tobacco 
fertilised with barnyard manure than with tobacco grown with other fertilisers. 
When it is considered that, commercially, tobacco is divided into four classes, viz. : 
cigar, cigarette, snuff and export, it becomes evident that the systematic observations as 
briefly described are invaluable to growers, who must, of necessity, produce tobacco suitable 
to the requirements of the market. 
THE LAC INDUSTRY OF INDIA. 
The resin and dye produced by the lac insect, Tachardia iacca , have been employed by 
the natives of India from very remote times, references to these materials being known in 
Sanskrit literature at least 4,000 years old. Formerly the dye was the more important 
product, and at one time to a considerable extend supplanted cochineal, even in European 
dyehouses, but with the advent of the coat-tar dyes, both these natural dyestuffs have 
practically passed out of use, and lac dye is now merely a bye-product in the manufacture of 
shellac. The information available regarding the life history of the insect, the chemistry of 
the resin produced by it, and the statistics of commerce in this material, have recently been 
collected in a special number of the Agricultural Ledger {No. 9, 1901), from which the 
following resume has been compiled. 
The insect which produces lac belongs to the zoological order Iletnipterce and is, 
therefore, a near relative of the cochineal insect. Like the latter it inhabits by preference 
special trees, such as Butea frondosa (palas), Acacia arabica (babul), Pterocarpus marsupmnt 
(kino tree), Shorca robusta (sal tree), Sisyphus jujuba , and various species of Ficus. On 
the young twigs of such plants the lame settle, and fix themselves by inserting their hollow 
probosces in the bark and so suck out the sap, Avhich, in the process of digestion, undergoes 
considerable change, and is excreted in the form of a resin with which each larva rapidly 
becomes completely incrusted. Meanwhile the larvae, which were at first apparently all of 
one kind, have developed into insects of two sexes, the males being winged and the females 
wingless. The former escape from their resinous incrustations, while the latter produce eggs 
and complete their life history in the position first taken up by them. Each female produces 
about 1,000 eggs, the formation of the latter being preceded by the appearance of a bright 
red colouring matter which is probably intended to serve as nutriment for the young lame, 
since these remain in situ until mature and able to creep to a new portion of the twig, where 
they repeat the life cycle outlined in the foregoing paragraph. Where the lac insect is propa- 
gated for the sake of its resin, the twigs are cut just before the lame are mature, and these 
cuttings are placed on fresh twigs which then rapidly become infested by the escaping 
swarms. Two broods of larvae are produced each year, the first early in July and the 
second early in December. The most serious enemies of the lac insect are ants and moths, 
since the former attack the females in order to obtain the sweet juice upon which the lame 
are fed, while certain species of moth eat both the females and the young lame. These 
pests are difficult to exterminate, since the application of any of the usual insecticides would 
destroy both victim and aggressor. 
It is uncertain whether or not the continued propagation of the lac insect upon trees 
seriously injures the latter ; according to Sir William Jones {Asiatic Researches , 11. 1789, 361), 
trees are frequently destroyed in this way, but McKee {Indian Forester, Vol. 1. page 269), is 
of opinion that no great harm is done, although, probably, both the host and the insect 
benefit when the tree is regularly pruned in order to encourage the formation of new branches, 
and Ridley {Indian Forester , xxir., 440), has shown that in many cases the damage to the 
tree is done not by the insect but by the carelessness of the native lac collectors. 
In the original article, which extends to 350 pages, a considerable amount of space is 
devoted to descriptions of the methods of propagation and collection in vogue in the 
different provinces of India and to the extent of the local trade, but as this portion 
contains no information of general interest it may be omitted from the present summary. 
The lac is collected just after the swarming seasons by cutting off the twigs bearing the 
resinous incrustations, which are often sold in the bazaars without further preparation under 
the name “ stick lac.” In the native factories this material is crushed in grain mills, whereby 
the resin is ground into a rough powder, which is freed from wood and refuse by sifting, so 
forming seed-lac ; the latter is then macerated for a day in water and finally ground under 
water in an exceedingly primitive manner. The liquor so produced is of a bright purple 
colour, and is the source of the lac dye which was formerly an article of commerce. The 
washed seed-lac is next mixed with a certain small quantity of orpiment, in order to give the 
finished shellac a pale straw colour, and about three per cent, of common resin is added in 
order to lower the melting point and make the material workable in the processes through 
which it subsequently passes. The mixture is then packed into a narrow cloth bag from ten 
to twenty feet in length, which is held in front. of a long shallow coke fire whereby the resin 
is melted. The bag of resin is manipulated by two men who twist it in opposite directions, 
I 
