Scientific American Supplement, No. 447, July 26, 1884
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Various >> Scientific American Supplement, No. 447, July 26, 1884
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[Footnote 1: SUPPLEMENT, No. 446, page 7125.]
We call those diseases "parasitic" that are occasioned by the
introduction of a living organism into the bodies of animals. Although a
knowledge of such diseases is easy where it concerns parasites such as
acari and worms, it becomes very difficult when it is a question of
diseases that are caused by the Bacteriaceae. In fact, the germs of these
plants exist in the air in large quantities, as is shown by the analysis
of pure air by a sunbeam, and we are obliged to take minute precautions
to prevent then from invading organic substances. If, then, during an
autopsy of an individual or animal, a microscopic examination reveals
the presence of microbes, we cannot affirm that the latter were the
cause of the affection that it is desired to study, since they might
have introduced themselves during the manipulation, and by reason of
their rapid vegetation have invaded the tissues of the dead animal in
a very short time. The presumption exists, nevertheless, that when
the same form of bacteria is present in the same tissue with the same
affection, it is connected with the disease. This was what Davaine was
the first to show with regard to _Bacillus anthracis_, which causes
charbon. He, in 1850, having examined the blood of an animal that had
died of this disease, found therein amid the globules (Fig. 1), small,
immovable, very narrow rods of a length double that of the blood
corpuscles. It was not till 1863 that he suspected the active role of
these organisms in the charbon malady, and endeavored to demonstrate it
by experiments in inoculation. Is the presence of these little rods in
the blood of an animal that has died of charbon sufficient of itself to
demonstrate the parasitic nature of the affection? No; in order that
the demonstration shall be complete, the bacteria must be isolated,
cultivated in a state of purity in proper liquids, and then be used
to inoculate animals with. If the latter die with all the symptoms
of charbon, the demonstration will be complete. Davaine did, indeed,
perform some experiments in inoculation that were successful, but his
results were contradicted by the experiments of Messrs. Jaillard and
Leplat, and those of Mr. Bert concerning the toxic influence of oxygen
at high tension upon microbes. As Davaine was unable to explain the
contradiction between his results and those of Messrs. Jaillard, Leplat,
and Bert, minds were not as yet convinced, notwithstanding the support
that his ideas received from Mr. Koch's researches.
In 1877 Mr. Pasteur took up Davaine's experiments, and confirmed his
affirmations step by step by employing the method of culture that he had
used with such success in his studies upon fermentation. He isolated
Davaine's bacterium by cultivating it in a decoction of beer yeast that
had been previously sterilized (Fig. 2); and after from ten to twenty
cultures, he found that a portion of the liquid containing a few
bacteria, when used for inoculating a rabbit, quickly caused the latter
to die of charbon, while the same liquid, when filtered through plaster
or porcelain, became harmless.
Davaine's bacterium develops exclusively in the blood, and is never
found at any depth in the tissues. This is due to the fact that the
alga, having need of oxygen in order to live, borrows its flow from the
blood, and thus extracts from the globules that which they should have
carried to the tissue. The animal therefore dies asphyxiated. It is on
account of the absence of oxygen in the blood that the latter assumes
the blackish-brown color that characterizes the malady, and that has
given its name of _charbon_ (coal).
The parasitic nature of charbon was therefore absolutely demonstrated,
first, by the constant presence of _Bacillus anthracis_ in the blood of
anthracoid animals, and second, by the pure culture of the parasite and
the inoculation of animals with charbon by means of it.
Davaine began the demonstration in 1863, and Pasteur finished it in
1877. These facts are now incontestable; yet, to show how slowly truth
is propagated, even in these days of telegraphs and telephones, there
might have been read a few months ago, in an interesting article on
microbes, by Dr. Fol, a distinguished savant, the statement that charbon
and tuberculosis were discovered by Dr. Koch!
New parasitic affections, whose existence was suspected, were soon
discovered and scientifically demonstrated, such, for example, as
septicaemia, or the putrefaction which occurs in living animals, which in
ambulances causes so fearful havoc among the wounded, and which proceeds
from _Bacillus septicus_. This parasite exhibits itself under the form
of little articulated rods that live isolated from oxygen in the mass of
the tissues, and disorganize the latter in disengaging a large quantity
of putrid gas. Other parasites of this class are the _micrococcus_ of
chicken cholera (Fig. 3), the _micrococcus_ of hog measles, and the
_Spirochoete Obermeieri_ of recurrent fever, discovered by Obermeier
(Fig. 5).
Besides these, there are a certain number of maladies that seem as if
they must be due to the Bacteriaceae, although a demonstration of the
fact by the method of cultures and inoculation has not as yet been
attempted. Among such, we may cite typhoid fever, diphtheria, murrain,
tuberculosis (Fig. 4), malarial fever (Fig. 6), etc.
As may be seen, the list is already a long one, and it tends every day
to still further increase. All the progress that has been made in so
few years in our knowledge of contagious or epidemic diseases is due
exclusively to M. Pasteur and the scientific method that he introduced
through his remarkable labors on fermentation. Now that we know our most
formidable enemies, how shall we defend ourselves against them?
As we have seen, bacteria exist everywhere, mixed with the dust that
interferes with the transparency of the air and covers all objects; and
they are likewise found in water.
Under normal conditions, our body is closed to these organisms through
the epidermis and epithelium, and, as has been shown by Mr. Pasteur, no
bacteria are found in the blood and tissues of living animals. But let a
rupture or wound occur, and bacteria will enter the body, and, when once
the enemy is in place, it will be too late. One sole chance of safety
remains to us, and that is that in the warfare that it is raging against
our tissues the enemy may succumb. M. Pasteur has shown that the blood
corpsucles sometimes engage in the contest against bacterides and
come off victorious. In fact, chickens are proof against poisoning by
charbon, because, owing to the high temperature of their blood, the
bacterides are unable to extract oxygen from the corpuscles thereof.
But, if the chickens be chilled, the conditions are changed, and they
will die of charbon just as do cattle and sheep; but, as the result of
the contest cannot always be foreseen, it is necessary at any cost to
prevent bacterides from entering the body.
[Illustration: I. Bacteria of charbon (_Bacillus antracis_.) II. The
same cultivated in yeast. III. The _Micrococcus_ of chicken cholera. IV.
The _Bacillus_ of tuberculosis. V. The _Spirillun_ of recurrent fever.
VI. The _Bacillus_ of malaria.]
Under ordinary circumstances a severe hygiene will suffice to preserve
us; if a wound is received it should be washed with water mixed with
antiseptics, such as phenic acid, borax, or salicylic acid. If water is
impure, it must be boiled and then aerated before it is drunk. If the
air is the vehicle of the germs of the disease, it will have to be
filtered by means of a muslin curtain kept wet with a hygroscopic
solution, glycerine for example. Finally, when, after an epidemic,
contaminated apartments are to be occupied, the walls and floor and the
clothing must be washed with antiseptic solutions whose nature will vary
according to circumstances--steam charged with phenic acid, water mixed
with a millionth part of sulphuric acid, boric acid, ozone, chlorine,
etc.
These preventives only prove efficient on condition that they be used
persistently. Let our vigilance be lacking for an instant, and the enemy
will enter to work destruction, for it only requires a spore less than
a hundredth of a millimeter in diameter to produce the most serious
affections.
Fortunately, and it is again to Mr. Pasteur that we owe these wonderful
discoveries, the parasitic microbes themselves, which sow sickness and
death, may, through proper culture, become true vaccine viri that are
capable of preserving the organism against any future attack of the
disease that they were capable of producing; such vaccine matters have
been discovered for charbon, chicken cholera, the measles of swine, etc.
When the _micrococcus_ of chicken cholera (Fig. 3.) is cultivated, it
is seen that the activity of the microbe in cultures exposed to the air
gradually diminishes. While a drop of the liquid would, in twenty-four
hours, have killed all the chickens that were inoculated with it, its
effect after two, three, or four days considerably diminishes, and an
inoculation with it produces nothing more than a slight indisposition in
the animal, and one that is never followed by a serious accident. It is
then said that the virulence of the microbe is attenuated.
The air is the agent of this transformation that gradually renders the
bacteria benign, for in cultures made under the same circumstances as
the preceding, but with the absence of air, the activity of these algae
is preserved for days or weeks, and they will then cause death just as
surely as they would have done at the end of one day.
What is remarkable is that animals inoculated with the attenuated
_micrococcus_ become for a varying length of time refractory to the
action of the most formidable parasites of this kind. Mr. Pasteur has
discovered two such vaccine viri--one for chicken cholera and the other
for charbon. His results have not been accepted without a struggle, and
it required nothing less than public experiment in vaccination, both in
France and abroad, to convince the incredulous. There are still people
at the present time who assert that Mr. Pasteur's process of vaccination
has not a great practical range! And yet, here we have the results; more
than 400,000 animals have been vaccinated since 1881, and it has been
found that the mortality is ten times less in these than in those that
have not been vaccinated!
An impetus has now been given, and we can look to the future with
confidence, for, if our enemies are numerous, the use of a severe
hygiene and preventive vaccination will permit us to gradually free
humanity from the terrible scourges that sap the sources of fortune and
life.--_Science et Nature_.
* * * * *
THE WINE FLY.
At the last meeting of the New York Microscopical Society, a paper
was read by Dr. Samuel Lockwood, secretary of the New Jersey State
Microscopical Society. His subject was the Wine Fly, _Drosophila
ampelophila_. The paper was a contribution to the life-history of this
minute insect. He had given in part three years to its study, beginning
in September, 1881, when nothing whatever of its life-history seemed to
have been known. In October the flies attacked his Concords. He found
upon a grape which he was inspecting with a pocket-lens an extremely
small white egg; but lost it. The grapes when brought on the table were
infested by the flies, which proved to be the above mentioned species.
When driven from the grapes they would fly to the window, where he
captured two of them These were placed in a jar with a grape for food.
In two days he found one egg on the outer skin of the grape. The laying
was kept up for four or five days, until there were about thirty, some
on the outside of the grape and some at an opening where the two flies
had fed. The egg had a pair of curious suspenders near the end where
the mouth of the larva would develop. These suspenders were attached at
their ends to the grape, but where the egg was laid in the soft part of
the fruit the suspenders were spread out at the surface; thus the larva
would emerge clean from the shell. The egg was 0.5 mm. in length, and
about a fourth of that in width. The larva when grown was at least four
times as long as the egg. As the larva burrowed in the juices of the
fruit, two quite prominent breathing tubes at the posterior end were
kept in the air. Between these cardinal tubes were several teat-like
points, much smaller, but having a similar function.
The larvae appeared in five days after the eggs were laid. In about as
many more days the puparium state would be entered, and in about six
days more the fly or imago would appear. In ovipositing the suspensors
would leave the oviparous duct last. The paper claimed that the curious
shape of the egg compelled the female to oviposit slowly, as it took
time for the egg to assume its form; hence, the eggs were not laid in
strings or masses, but singly and at considerable intervals.
The flies are very hairy, especially the females. The neck and even the
eyes are very hirsute. The eyes are red, quite large and pretty, though
somewhat _outre_ under the microscope, for from between the little
lenses are projecting, straight, stiff hairs. As the insect is quite
active, it must be that this fringing of the tiny eyelets with hair does
not materially obscure its vision. When the minuteness of this singular
arrangement is considered, it is surely remarkable. This general
hairiness of the female especially, and that about the head, neck, and
forward part of the thorax, stands correlated to a beautiful structure
found only in the male, which has on the tarsus of each leg in the
forward pair what the lecturer called a sexual comb. It is a beautiful
comb of a very dark brown color, each comb having ten pointed and strong
teeth. In the nuptial embrace these combs are fixed in the hairy front
of the thorax of the female, thus becoming little grapnels.
The flies love any vegetable substance in fermentation, whether acetic
or vinous. Hence it will abound about cider mills, swarm on preserves in
the pantry, and in cellars or places where wine is being made or stored.
The paper showed the tendency of the glucose in the over-ripe grape
to the vinous ferment, and that the fly delighted in it. A singular
accident showed how they loved even the very high spirits. In making
some of the mounts shown to the society, Dr. Lockwood had left a bottle
of 90 per cent. alcohol uncorked over night. Next morning he was
astonished to find his alcohol of a beautiful amethystine color, and the
cork out. Inspection showed a number of these tiny creatures, which,
when filled with the purple juice of the grape, had smelt the alcohol
in the open bottle, and had gone in to drink. They had ignominiously
perished, and had given color to the liquid.--_Micro. Journal_.
* * * * *
[NATURE.]
THE "POTETOMETER," AN INSTRUMENT FOR MEASURING THE TRANSPIRATION OF
WATER BY PLANTS.
In view of the interest now attaching to recent advances in vegetable
physiology, it seems not unlikely that a description of the instrument
bearing the above name, lately published by Moll (_Archives
Neerlandaises_, t. xviii.), will serve as useful purpose. The apparatus
was designed to do away with certain sources of error in Sachs'
older form of the instrument, described in his "Experimental
Physiologie"--errors chiefly due to the continual alteration of pressure
during the progress of the experiment.
As shown in the diagram, the "potetometer" consists essentially of a
glass tube, a d, open at both ends, and blown out into a bulb near the
lower end; an aperture also exists on either side of the bulb at or
about its equator. The two ends of the main tube are governed by the
stopcocks, a and d, and the greater length of the tube is graduated. A
perforated caoutchouc stopper is fitted into one aparture of the bulb,
e, and the tube, g k, fits hermetically to the other. This latter tube
is dilated into a cup at h to receive the caoutchouc stopper, into which
the end of the shoot to be experimented upon is properly fixed.
The fixing of the shoot is effected by caoutchouc and wire or silk, as
shown at i, and must be performed so that the clean-cut end of the
shoot is exactly at the level of a tube passing through the perforated
stopper, e, of the bulb; this is easily managed, and is provided for by
the bending of the tube, g h. The tube, f, passing horizontally through
the caoutchouc stopper, e, is intended to admit bubbles of air, and so
equalize the pressure and at the same time afford a means of measuring
the rapidity of the absorption of water by the transpiring shoot. This
tube (see Fig. 2, f) is a short piece of capillary glass tubing, to
which is fixed a thin sheath of copper, b', which slides on it, and
supports a small plate of polished copper, a', in such a manner that the
latter can be held vertically at a small distance from the inner opening
of the tube, and so regulate the size of the bubble of air to be
directed upward into the graduated tube, a b.
[Illustration]
The apparatus is filled by placing the lower end of the main tube under
water, closing the tubes, f and i (with caoutchouc tubing and clips),
and opening the stopcocks, a and d. Water is then sucked in from a, and
the whole apparatus carefully filled. The cocks are then turned, and the
cut end of the shoot fixed into i, as stated; care must be taken that no
air remains under the cut end at i, and the end of the shoot must be at
the level, k l. This done, the tube, f, may then be opened.
The leaves of the shoot transpire water, which is replaced through the
stem at the cut end in i from the water in the apparatus. A bubble of
air passes through the tube, f, and at once ascends into the graduated
tube, a c. The descent of the water-level in this tube--which may
conveniently be graduated to measure cubic millimeters--enables the
experimenter at once to read off the amount of water employed in a given
time.
It is not necessary to dwell on obvious modifications of these
essentials, nor to speak of the slight difficulties of manipulation
(especially with the tube, f). Of course the apparatus might be mounted
in several ways; and excellent results for demonstration in class could
be obtained by arranging the whole on one of the pans of a sensitive
balance. H. MARSHALL WARD.
Botanical Laboratory, Owens College.
* * * * *
BOLIVIAN CINCHONA FORESTS.
The great progress made in the acclimation of cinchona trees in India,
Ceylon, and elsewhere has awakened the governments of countries where
the plants are indigenous to the necessity of conserving from reckless
destruction, and replanting denuded forests, so as to be able to keep up
the supply of this valuable product.
In Bolivia, since 1878, according to the report of the Netherlands
Consul, private individuals and land owners have taken up the question
with great earnestness, and at the present time on the banks of the
Mapiri, in the department of La Paz, there are over a million of young
trees growing.
New plantations have also sprung up in various other localities, either
on private ground or that owned by Government. The competition of India
and Ceylon in supplying the markets has had also the effect of inducing
more care in collecting and also of revisiting old spots, often with the
result of a rich harvest of bark which had been left on partly denuded
trunks, and the opening up of new localities. The new shoots springing
up from the old stumps have yielded much quill bark, and the root bark
of the old stumps has also been utilized.
The replanting entails very little expense. The Indian tenant on an
estate has a house and land from the owner (hacienda) of the estate. For
this he binds himself to work for two to four days a week, at from 28 to
36 cents per day, women and children obtaining 16 to 21 cents per day.
Thus the planting, weeding, etc., during the first two years is
but nominal in expense; after this period the trees may be left to
themselves.
On Government land the expense is greater, as, after an application
being made, the land is put up to public auction, and may fetch a
very low or higher price according to the bidding. The land secured,
contracts are made with natives of the lower class to clear the forest
and plant cinchona. The contracts are often sublet to Indians. The
young plants are planted from five to six feet apart, with banana trees
between, on account of their rapid growth and the shade the latter
afford. From March to June, after the wet season is over, is the best
time for planting, and the contractor keeps the plantation free from
weeds and in good order for twelve months, when it is handed over to the
owner. The following is given as the cost of the Mapiri River plantation
of an area from 60 or more miles in extent:
Ground. $1,200
300,000 plants at $0.14. 42,000
Superintendent, buildings, etc. 4,400
Interest. 4,800
-------
Total. $52,400
Till the plants are above two years of age, they are liable to die from
drought or the attacks of ants, and during 1878 many thousands died from
these causes. At the end of the fourth year some proprietors begin to
collect the quill bark by the method of coppicing.
It is feared by some that, should this new venture be successful, it
will prove a dangerous rival to the plantations of India, Ceylon, and
Java, and lower the price of bark considerably.--_Jour. Society of
Arts_.
* * * * *
FERNS.
_N. Davallioides Furcans._--Among the many crested ferns in cultivation,
this, of which the annexed is an illustration, is one of the most
distinct; so different indeed it is from the type, that it is
questionable if it really is a form of it; the most essential
characteristic, that of the fructification at the extreme edge of the
lobes of the pinnae, is altogether absent, and the whole habit of the
plant is also thoroughly distinct. It is of equally robust growth,
but its handsomely arching fronds, which are from 3 feet to 4 feet
in length, are produced in great abundance from a central tuft or
agglomeration of crowns. Its most distinct characteristic is the
furcation of the pinnae, which are all of the same dimensions, whether
sterile or fertile; they are all opposite and closely set along the
mid-rib, whereas those of N. davallioides are set much further apart.
In the barren pinnae which are only situated on the lower portion of the
frond, and which generally are only few in number, the furcation is
rudimentary; in the fertile pinnae it is twice and even three times
repeated in the extremities of the first division, becoming more complex
toward the point of the frond, where it often forms quite a large
tassel, whose weight gives the fronds quite an elegant, arching habit.
On that account this plant is valuable for growing in baskets of large
dimensions, in which it shows itself off to good advantage, and never
fails to prove attractive. Although it produces spores freely, it is
best to propagate it by means of the young plants produced from rhizomes
in the ordinary way, on account of the extreme variations which take
place among the seedlings, a small percentage only of which are
possessed of the true character of the parent plant. Stove.--_The
Garden._
[Illustration: NEPHROLEPIS DAVALLIOIDES FURCANS.]
_N. Duffi_.--This pretty, neat-habited species, of which an
illustration, kindly lent us by Mr. Bull, appears in another place, is a
native of the Duke of York's Island, in the South Pacific Ocean, and is
undoubtedly one of the most interesting of the whole genus. Its compact
habit, its comparatively small dimensions, and the bright, glossy color
of its beautifully tasseled fronds render it a most welcome addition to
a group of ferns naturally rich in decorative plants. Its curiously and
irregularly pinnate fronds are borne on slender stalks, terete toward
the base, and covered with reddish brown, downy scales, instead of being
produced loosely, as in most other Nephrolepises; these are densily
crowded, and the outcome of closely clustered crowns. They measure from
15 inches to 18 inches long, and are terminated by very handsome massive
crests, which vary in size according to the temperature in which the
plant is grown. We have at different times heard complaints of these
fronds being simply furcate, when the same plant, after being subjected
to a greater amount of heat and moisture, produced fronds very heavily
tasseled, and partaking of an elegant vase-shaped appearance. In fact,
nothing short of the moist heat of a stove will induce it to show its
characters in their best condition. The pinnae, which are small, of
different sizes, rounded and serrated at the edges, are produced in
pairs, one overlying the other, and, curiously enough, those on the top
are the largest. The pairs are sometimes opposite, but mostly alternate,
distant toward the base, approximate higher up, and crowded and
quite overlapping in the crested portion of the frond. This, being
a thoroughly barren kind, can only be propagated by division of the
crowns, an operation easily done at any time of the year, but most
safely in early spring and by young plants produced from the rhizomes,
which, however, are produced much more sparingly than in any other
species. It is also one of the best adapted for pot or pan culture, its
somewhat upright habit making it less suitable for baskets, brackets,
and wall covering than other species. Stove.--_The Garden_.
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