_NATURE’S REVENGES: THE SLEEPING SICKNESS._
Among the strange and mysterious diseases to which mankind is
subject in regions less familiar to the civilised world than Western
Europe, none is stranger or more appalling in its quiet, inexorable
deadliness than the Sleeping Sickness of the West African coast.
Apparently it has existed among the natives of that region from
time immemorial; but the first printed record we have of it is due
to Winterbottom, who, writing in 1803 of Sierra Leone, said, “The
Africans are very subject to a species of lethargy which they are
much afraid of, as it proves fatal in every instance.” One of the
latest notices of the disease, before it became the subject of active
investigation within the last five years, is that of Miss Kingsley,
who saw a few cases near the Congo estuary, but, though she was
impressed by the mysterious fatality of the disease, she did not
describe it as very prevalent or as a general source of danger to
life. The opening up of the Congo basin and increased familiarity
with the inner lands of the West African coast have shown that this
disease is widely scattered--though rarely so abundant as to be a
serious scourge--through the whole of tropical West Africa. Writers
in the early part of the last century described the disease as
occurring in the West Indies and in Brazil. Its presence was almost
certainly due, in those days of the slave trade, to the importation
of negroes already infected with the disease; and a curious theory
obtained some favour, according to which the sleeping sickness of
the West Indian slaves was a kind of nostalgia, and, in fact, the
manifestation of what is sometimes called “a broken heart.”
The signs that a patient has contracted the disease are very obvious.
They are recognised by the black people, and the certainly fatal
issue accepted with calm acquiescence. The usually intelligent
expression of the healthy negro is replaced by a dull apathetic
appearance; and there is a varying amount of fever and headache.
This may last for some weeks but is followed more or less rapidly
by a difficulty in locomotion and speech, a trembling of the tongue
and hands. There is increased fever and constant drowsiness, from
which the patient is roused only to take food. At last--usually after
some three or four months of illness--complete somnolence sets in;
no food is taken; the body becomes emaciated and ulcerated; and the
victim dies in a state of coma. The course of the disease, from the
time when the apathetic stage is first noticed, may last from two to
twelve months.
It is this terrible disease which has lately appeared on the shores
of the Victoria Nyanza, in the kingdom of Uganda, administered by
the British Government. Until the early part of the year 1901 there
was not the slightest suspicion that sleeping sickness occurred
in any part of the Uganda Protectorate; nor was it known in East
Africa at all, any more than in the north and south of that great
continent. It seems gradually to have crept up the newly opened
trade-routes of the Congo basin, and thence to have spread into the
west of Uganda, the territory known as Busoga. Numbers of Soudanese
and Congo men are known to have settled in this region after the
death of Emin Pasha. First noticed in 1901, it was estimated in
June 1902, by the Commissioner of Uganda, writing officially to the
Marquess of Lansdowne, that 20,000 persons had died of this disease
in the district of Busoga alone, and several thousands in the more
eastern portion of Uganda. At this moment it is probable that the
number of deaths in this region due to sleeping sickness since 1901
amounts to more than 200,000; and this though, most fortunately,
the disease has not yet spread eastward from Uganda into British
East Africa,[23] nor, so far as has been reported, down the Nile. No
curative treatment for the disease has yet been discovered; nor is
there any authenticated instance of recovery.
The appalling mortality produced by this disease in Central Africa
naturally caused the greatest anxiety to his Majesty’s Government,
which had but just completed the railway from the East Coast to the
shores of lake Victoria Nyanza, and had established a prosperous and
happy rule in that densely populated region. The official medical
men on the spot, though capable and experienced practitioners,
were unable to cope with this new and virulent outbreak. The
Foreign Office, having no imperial board of hygiene and medical
administration to apply to in this country, sought the assistance of
the Royal Society of London.
A committee of that society had already undertaken the study of
malaria at the request of the Secretary of State for the Colonies,
and had sent out young medical men as a commission to make certain
enquiries and experiments on that subject and report to the
committee in London. The sleeping sickness enquiry was undertaken
by the same committee; but unfortunately very insufficient funds
were placed at its disposal. When the South African cattle-owners
found their herds threatened six years ago by a new form of mortal
disease--‘the East Coast fever’--the South African Government
accepted the offer of Dr. Robert Koch, of Berlin, to undertake the
investigation of the disease and the discovery, if possible, of a
remedy, for the sum of £10,000. No such sum was at the disposal
of the committee of the Royal Society. They were obliged to send
out young and enterprising medical men, practically without pay or
reward, to see what they could do in the way of determining the cause
of, and, if possible, the remedy for, the terrible sleeping sickness
raging in Uganda and destroying daily hundreds of British subjects.
The committee set to work in the summer of 1902, and sent out Drs.
Low, Christy, and Castellani to Entebbe, the capital of Uganda.
The guesses as to the cause and nature of sleeping sickness at the
time when this commission set forth were very various. Some highly
capable medical authorities held that it was due to poisonous food.
The root of the manioc, on which the natives feed, was supposed to
become infected by some poison-producing ferment. A more generally
received opinion was that it was caused by a specific bacterium which
invades the tissues of the brain and spinal cord. Several totally
different micro-organisms of this sort had been described with equal
confidence by French and Portuguese investigators as the cause of the
sleeping sickness studied by them in West Africa or on the Congo. Sir
Patrick Manson, the head of the British Colonial medical service, an
authority of great experience in tropical disease, had put forward
the suggestion that the sleeping sickness was due to the infection
of the patient by a minute thread worm (allied to the ‘vinegar-eel,’
and one of a great class of parasites) which he had discovered in the
blood of negroes and had named _Filaria perstans_.
The occurrence of minute worms (true worms, neither unicellular
plants nor protozoa) in the blood of man was first made known by Dr.
Timothy Lewis, who described the _Filaria sanguinis hominis_, as well
as some other most important blood-parasites, some years ago (1878),
when officially engaged in an enquiry into the cause of cholera in
Calcutta. Subsequently, in China, Manson found that these little
blood-worms were sucked up by mosquitoes when gorging themselves
on the blood of a patient. It is, indeed, difficult to imagine
how they should escape passing into the mosquito with the blood.
Manson suggested that the minute worms (known to be the embryos of
a worm which, when adult, is about one fifteenth of an inch long)
are obliged to pass through a mosquito in order to accomplish their
development; but no proof of this suggestion has ever been made.
We know by abundant and repeated demonstration and experiment that
another blood-parasite--the malaria parasite--must pass through a
mosquito, in whose body it develops, and by which it is carried to a
new victim of infection. This was suspected long ago by both peasants
and doctors, and experimentally proved by Ross; but no such proof
has been given of the relation of Lewis’s blood-worm to a mosquito.
The so-called _Filaria perstans_, discovered by Manson in the blood
of negroes, appears to be very different from the _Filaria sanguinis
hominis_ of Lewis. It is not known how it gets into the blood; and
it is very astonishing, and much to be regretted, that none of the
medical men who have had it under observation have given a proper
anatomical account of it. It appears that this worm is very common
in the blood of negroes in tropical Africa; and as it was found
in several cases in the blood of individuals attacked by sleeping
sickness, Sir Patrick Manson was justified in entertaining the view
that this parasite was the cause of the disease.
One of the first results obtained by the commission sent by the Royal
Society committee to Uganda was the proof--which had, indeed, been
already furnished by the resident medical officers of the Uganda
Protectorate--that _Filaria perstans_, though remarkably abundant
in the blood of the negroes of Uganda, can have nothing to do with
sleeping sickness, since, though it often occurs in persons attacked
with that disease, it also exists in districts where sleeping
sickness is unknown; and, further, many cases of sleeping sickness
have been observed in which no _Filaria perstans_ has been discovered
in the blood or other parts of the body.
While Drs. Low and Christy occupied themselves with settling
this question as to the connexion of _Filaria perstans_ with the
disease and carried out a careful study of its clinical aspects,
Dr. Castellani examined the brain and spinal cord of those who
died from sleeping sickness, for bacteria. He found again and
again an extremely minute globular vegetable parasite--of the kind
known as streptococcus--which he concluded to be the cause of the
disease, although he had not produced the disease experimentally by
inoculating an animal with this microbe.
In the early part of 1903 these were the only results obtained by
some six months’ work of the medical men sent out by the Royal
Society’s committee; and it was felt that something more must be
done. The investigation of a disease hitherto little known and
studied is one of the most difficult tasks in the world, requiring
the highest scientific qualities. Any serious attempt to deal with
the sleeping sickness in Uganda would, it was at length recognised,
require the dispatch of a man of proved capacity and experience,
provided with full powers and with trained men as his assistants. No
such men are provided by the public service of the British Empire.
To detach a medical man of recognised insight and experimental skill
from his practice--even were it possible to find one specially
qualified for the present enquiry--would involve the payment of a
large fee, which neither the Royal Society nor the Foreign Office
could command.
What, then, was to be done? Fortunately there was one man in the
public service, recently appointed to be one of the chiefs of the
educational arrangements of the Army Medical Department, who had
shown himself to be especially gifted in the investigation of
obscure diseases. This was Colonel David Bruce, F.R.S., who, some
fifteen years ago, established the existence of Malta fever, as
an independent disease, by his clinical observations and by the
isolation and cultivation of the parasitic bacterium causing it;
and who, further, when employed by the governor of Zululand a few
years later (1895) to investigate the celebrated tsetze-fly disease
of South Africa, had discovered, contrary to the assertions and
prejudices of a large number of African sportsmen and explorers, that
the horse and cattle disease known as nagana or tsetze-fly disease
was due to the presence in the blood of the affected animals of a
peculiar cork-screw-like animal parasite, the _Trypanosoma Brucei_.
This is carried by the bite of the tsetze-fly from the blood of wild
game, such as buffalo and antelope, where it does no harm, to the
blood of domesticated animals, in which it multiplies and proves to
be the source of a deadly poison causing death in a few weeks. The
experiments by which Colonel Bruce demonstrated this relationship of
tsetze-fly, trypanosome parasite, wild big game, and domesticated
animals, were universally regarded as masterly both in conception and
execution, and absolutely conclusive.
The committee of the Royal Society came to the conclusion that the
thing to be done was to get Colonel Bruce to consent to proceed
to Uganda, and to recommend the Foreign Office to obtain from the
War Office the temporary detachment of Colonel Bruce for this
service. Accordingly Colonel Bruce arrived in Uganda in the middle
of March, 1903. Dr. Low and Dr. Christy had already departed,
but Dr. Castellani was still at Entebbe engaged in the study of
his streptococcus. He mentioned to Colonel Bruce on his arrival
that he had on more than one occasion seen a trypanosome in the
cerebro-spinal fluid of negroes suffering from sleeping sickness;
but, inasmuch as Dutton on the West Coast and Hodges in Uganda had
described a trypanosome as an occasional parasite in human blood,
he had not considered its occurrence in sleeping-sickness patients
as of any more significance than is the occurrence of _Filaria
perstans_. Castellani regarded the trypanosome, like the filaria,
as a mere accidental concomitant of sleeping sickness, the cause of
which he considered to be the bacterial streptococcus which he had so
frequently found to be present.
Naturally enough, Bruce was impressed by the fact that trypanosomes,
of the deadly nature of which he had had ample experience, had been
found, even once, in the cerebro-spinal fluid of sleeping-sickness
patients; and he immediately set to work to make a thorough search
for this parasite in all the cases of sleeping sickness; then under
observation at Entebbe. He generously allowed Castellani to take
part in the investigation, which resulted in the immediate discovery
of the trypanosome in the cerebro-spinal fluid of twenty cases, out
of thirty-four examined, of negroes afflicted with the disease;
whilst in twelve negroes free from sleeping sickness the trypanosome
could not be found in the cerebro-spinal fluid. Castellani returned
to Europe three weeks after Bruce’s experiments were commenced, and
announced the discovery, which has been, in consequence, erroneously
attributed to him, although mainly due to Bruce.
Bruce continued his work in Uganda until the end of August, 1903,
having been joined there by Colonel Greig of the Indian Army, who
has continued the work of the Royal Society’s commission since Bruce
left. Other valuable observations have been carried out by various
medical men officially connected with the Uganda Protectorate.
Bruce soon showed that in every case of sleeping sickness, when
examined with sufficient care, the trypanosome parasite is found to
be present in the cerebro-spinal fluid. He also showed that it is
absent from that fluid in all negroes examined who were not afflicted
with the disease, but made the very important discovery that the
trypanosome is present in the blood (not the cerebro-spinal fluid)
of twenty-eight per cent. of the population in those areas where
sleeping sickness occurs, the persons thus affected having none of
the symptoms of sleeping sickness, but being either perfectly healthy
or merely troubled with a little occasional fever. The subsequent
history of all the cases thus observed has not as yet been recorded.
But in many such, even in some Europeans, the earlier presence of
the trypanosome in the blood has been followed by its entry into the
cerebro-spinal lymphatics, and by the fatal development of sleeping
sickness.
As already indicated, it was found by Bruce, on recording the cases
of sleeping sickness brought into or reported in Entebbe, that there
were certain “sleeping-sickness areas” and other areas free from
sleeping sickness. The theory now took shape in Bruce’s mind that
the trypanosome first gets into the blood, and then after a time,
makes its way into the cerebro-spinal system, only then producing
its deadly symptoms. Very generally, when once in the blood, the
trypanosome multiplies itself, and sooner or later--apparently,
in some cases, even after two or three years--gets into the
cerebro-spinal fluid. It is probable that it may be destroyed by
natural processes in the human body before this final stage is
reached; and thus the infected person may recover and escape the
deadly phase of the disease. But nothing certain is known, as yet,
on this head. Later observations show that the trypanosome is found
alive and in large quantity in the lymphatic glands, especially those
in the region of the neck in infected persons. These glands were
known to be enlarged in persons suffering from the disease.
Colonel Bruce’s next step was to ascertain the mode in which the
trypanosome is introduced into the blood. Naturally he looked for a
kind of tsetze fly, such as carries the trypanosome in the nagana
disease of horses and cattle already studied by him in Zululand. It
is a fact that the _Glossina morsitans_ and _Glossina pallidipes_,
which are the tsetze flies of the “fly-districts” where nagana
disease is rife, are unknown in Central or Western Africa; and
also it is a fact that no tsetze fly had been observed in the
neighbourhood of the Victoria Nyanza when Colonel Bruce began his
enquiries. He employed, through the good-will of the native chiefs
and rulers, a large number of natives to collect flies throughout
the country forming a belt of twenty or thirty miles around the north
of the lake. Many thousands of flies were thus brought in, and the
localities from which they came carefully noted. Among these flies
Colonel Bruce recognised a tsetze fly; and when these collections
were received at the Natural History Museum in London, it was at once
determined by Mr. Austen, the assistant in charge of our collections
of Diptera (or two-winged flies), that the Uganda tsetze fly was
not the same species as that of Zululand and the fly country, but
a distinct species previously known only on the West Coast and the
Congo basin, and described by the name _Glossina palpalis_. The
story thus developed itself: the trypanosome of sleeping sickness
is probably carried by this West Coast tsetze fly just as the
trypanosome of nagana is carried in the south-east of Africa by the
_Glossina morsitans_ and _pallidipes_, the regular and original
“tsetze” flies.
Sleeping sickness thus presented itself as a special kind of human
tsetze-fly disease. To test this hypothesis, Colonel Bruce pursued
two very important and distinct lines of enquiry. In the first
place he found that those places on his map which were marked as
“sleeping-sickness areas” were precisely those places from which the
collected flies included specimens of tsetze fly, whilst he found
that there were no tsetze flies in the collections of flies brought
in by the natives from the regions where there was no sleeping
sickness.
His second test inquiry consisted in ascertaining whether the tsetze
flies of Uganda are actually found, experimentally, to be capable
of carrying the trypanosome from one infected person to another.
For this purpose it was necessary to make use of monkeys, certain
species of which were ascertained to be liable to the infection
of the sleeping sickness trypanosome when this was introduced by
means of injection through a syringe. Such monkeys were found to
develop the chief symptoms of sleeping sickness, and ultimately
died of the disease, their cerebro-spinal fluid being invaded by
the parasites. Accordingly it was possible to use monkeys as test
animals. It was found by Colonel Bruce that tsetze flies (_Glossina
palpalis_) which had been made to bite infected negroes could carry
the infection to the monkeys; and it was also found that even when
a number of tsetze flies, not specially prepared, were allowed to
bite a monkey, the latter eventually developed the trypanosome in its
blood and cerebro-spinal fluid, thus showing that the tsetze flies,
as naturally occurring in the country around Entebbe, contain many of
them, the trypanosome ready to pass from the fly to a human or simian
victim, when casually bitten by the fly.
Experiments such as these of infection by the fly, and the use of
monkeys in the research, require very great care; and it is quite
reasonable to ask that they shall be repeated and most carefully
checked before they are considered as demonstrative and absolutely
certain. It may, however, be considered as practically certain that
the sleeping sickness is due to the presence in the cerebro-spinal
fluid of quantities of a minute parasite, the _Trypanosoma
Gambiense_, which is carried from man to man by the _palpalis_ tsetze
fly, which sucks it up from the blood of an infected individual and
conveys it to previously uninfected individuals. The natives in
Uganda lie about and sleep under the shade of trees where the tsetze
flies are especially abundant; and they are quite indifferent to the
bites of flies of one kind and another.
It is the dislike to the mere touch of a fly, still more to its bite,
which has protected Europeans almost entirely from the sleeping
sickness. Unfortunately there is no immunity for Europeans in the
matter; and the existence of half a dozen or more cases of white
people infected with the trypanosome, who have ultimately died in
England or elsewhere in Europe from sleeping-sickness contracted
through the bite of a fly in Africa, is abundant proof that there is
not, as has been supposed, any special freedom from the disease for
white people.[24]
The foregoing description of the nature and mode of the infection
of sleeping sickness will not cause any astonishment to the layman
of the present day who knows anything of recent medical science. We
are all familiar with the danger of fly-bites, even in this country,
where deadly bacteria are occasionally carried by biting flies, such
as the horse-flies, into the human subject; and nowadays every one is
more or less familiar with the discovery of the minute blood-parasite
which causes malaria or ague and is carried by a particular kind
of gnat in the interior of which it multiplies by a process of
sexual conjugation. At the same time the reader who is interested in
sleeping sickness will probably desire to know more about the nature
of the tsetze flies and some further details as to the parasite
spoken of as trypanosome.
[Illustration: FIG. 48.
Tsetze flies--_Glossina morsitans_--magnified two diameters. This
is the “fly” of the Nagana or horse and cattle disease of South
Africa. The _Glossina palpalis_, which carries the _Trypanosoma
Gambiense_ causing sleeping sickness, is very closely similar to
it in appearance.]
The tsetze flies form a genus called by Wiedemann (in 1830)
“Glossina.” They are only found in Africa; and some seven species
in all are known. They are little bigger than a common house-fly,
and much like it in colour (fig. 48). They differ in appearance
from the house-fly in the fact that the wings, when the insect is
at rest, are parallel to one another, and slightly over-lap in the
middle line, instead being to a small extent divergent at their free
extremities. The bite, like that of all flies, is rather a stab than
a bite, and is effected by a beak-like process of the head, the blood
of the animal pricked in this way being drawn into the fly’s mouth
by a sucking action of the gullet. The tsetze flies appear to be
especially greedy and are said to gorge themselves to such an extent
that the blood taken in from one animal overflows the gullet, and
so contaminates the wound inflicted by the fly on the next animal
it visits. It is at the present moment assumed very generally that
this is the way in which infection is produced. But it is not at all
improbable that the trypanosome undergoes some kind of multiplication
and change of form when sucked into the tsetze fly as happens in the
case of the malaria parasite when swallowed by the _Anopheles_ gnat.
No such change has yet been discovered in regard to the trypanosome
of sleeping sickness: but it cannot be said that the matter has been
exhaustively studied, or that a negative conclusion is justified.[25]
[Illustration: FIG. 49.
The earliest discovered Trypanosome, described by Gruby in 1843
as “_Trypanosoma sanguinis_” and found by him in the blood of the
common esculent Frog.
It was not noticed again until it was re-discovered by Lankester
in 1871, who published the above figure of it in the _Quarterly
Journal of Microscopical Science_ in that year.]
As to the parasite itself--the trypanosome--a long and very
interesting story has now to be told. The first blood-parasite ever
made known to naturalists and medical men was that to which Gruby,
in 1843, gave the name _Trypanosoma sanguinis_. He found it in the
blood of the common frog. We have here reproduced a figure of this
original trypanosome (fig. 49). Similar parasites had been seen, but
not named, in the blood of fishes. These trypanosomes are all very
minute and of a somewhat elongated form, a fair average length being
one thousandth of an inch. They are simple protoplasmic animals,
consisting of one single nucleated corpuscle. The protoplasm is
drawn out at one end of the creature into a motile undulating thread,
and from the point where this joins the body a membranous undulating
crest extends along the greater part of the animal’s length. There
is no mouth, nutrition being effected by the imbibition of soluble
nutrient matter.
After a long interval Gruby’s trypanosome was re-discovered in 1871;
and then several kinds were described in the blood of tortoises,
fishes and birds. In 1878, Dr. Timothy Lewis found a parasite in the
blood of rats, at first in India, and subsequently in the common
rats of London sewers. This parasite resembles a trypanosome in
many respects (fig. 46A), but was very properly given a distinct
name by Savile Kent, who called it “Herpetomonas.” This name has,
however, been dropped; and the rat’s-blood parasite is spoken of as
a trypanosome. It is the _Trypanosoma Lewisii_, and was the first of
these trypanosomes to be found in the blood of a mammalian animal.
The _Trypanosoma Lewisii_ of the rat’s blood seems to do no harm
to the rat, in which it swarms, multiplying itself by longitudinal
fission; nor is it at present known to produce any trouble in other
animals when transferred to their blood. Similarly, the frog’s
trypanosome seems to exist innocently in the frog’s blood.
The next trypanosome discovered (1880) was, however found in the
blood of camels, horses, and cattle suffering from a deadly disease
known in India by the name “surra.” It is called _Trypanosoma
Evansii_, after the observer who detected it. Trypanosomes now began
to get a bad name, for the next was discovered in animals afflicted
by a North African disease known to French veterinaries as “dourine.”
This trypanosome was called _T. equiperdum_.
A little later, namely, in the year 1895, came Bruce’s discovery of
a trypanosome associated with a tsetze fly in the production of the
terrible nagana disease of the “fly-belts” of South Africa, which
renders whole territories impassable for horses or cattle (fig.
46B). The remarkable and important observation was made by Bruce
that this trypanosome (known as _T. Brucei_) inhabits the blood
of big game without injuring them, just as the rat’s trypanosome
inhabits the rat’s blood without producing disease; and that it is
only when the trypanosome is carried from these natural wild “hosts”
to domesticated animals introduced by man, such as horses asses,
cattle, and dogs, that disease results. The wild animals are “immune”
to Bruce’s trypanosome; the introduced animals are poisoned by the
products of its growth and fissile multiplication in their blood.
Since Bruce’s researches on nagana, a trypanosome, _T. equinum_ (fig.
46D), has been discovered in the horse-ranches of South America,
where it causes deadly disease, the _mal de caderas_, among the
collected horses; and a curiously large-sized trypanosome has been
found by Theiler in the blood of cattle in the Transvaal. Down to
a recent date no trypanosome had been found in the blood of man;
and indeed it is almost certain that none of the kinds hitherto
mentioned can survive in his blood. But in 1902 Dutton discovered
a trypanosome in the blood of a West African patient; and a few
other cases were noted. This trypanosome of human blood was called
by Dutton _T. Gambiense_. It was not found to be connected with any
serious symptoms, a little fever being the only disturbance noted.
It now, however, appears that this trypanosome in the blood is the
preliminary stage of the infection which ends in sleeping sickness;
and, as we have seen, in a population seriously attacked by sleeping
sickness, as is that of Uganda, as many as 28 per cent. of the people
have trypanosomes in their blood.
There is no ground at present known for distinguishing Dutton’s
_T. Gambiense_ of human blood from that which Bruce has found to
be so terribly abundant in Uganda, and to be the cause of sleeping
sickness. Indeed all the trypanosomes of the blood of the larger
mammalia are singularly alike in appearance; and the figure which is
here given (fig. 50) of the trypanosome of sleeping sickness (_T.
Gambiense_) might quite well serve to represent the _T. Evansii_ of
surra disease, the _T. Brucei_ of nagana disease, or the _T. equinum_
of the South American _mal de caderas_.
[Illustration: FIG. 50.
_Trypanosome Gambiense_, from the blood of men suffering from the
early symptoms of sleeping sickness. A, after Bruce and Navarro;
B, after Castellani. They show a large oval nucleus (drawn as a
black mass), and a small black “micronucleus,” or “blepharoplast”
in front.]
A most characteristic feature, which has been made out by the careful
study of these trypanosomes by means of colouring reagents and very
high powers of the microscope, is that, whilst there is a large
granular nucleus there is also a small body at the anterior end of
the animalcule which readily stains and is placed at the end of the
root (so to speak) of the vibratile _flagellum_ or free thread.
This smaller nucleus has been variously called the “micronucleus,”
the “centrosome,” and the “blepharoplast.” It is identical with a
structure similarly placed in non-parasitic microscopic animals
to which trypanosoma is undoubtedly related. We find it in the
phosphorescent noctiluca of our seas, and in various animalcules
called “Flagellata.”
[Illustration: FIG. 51.
The Trypanosome (_T. equiperdum_) of the disease called
“Dourine,” as seen alive in the blood of a rat, eight days after
inoculation.
A, the actively wriggling cork-screw-like parasites; B, the
blood-corpuscles of the rat. This figure, of comparatively low
magnification, gives an indication of the relative size of the
parasites and the blood-corpuscles.
The blood-corpuscles are about 1/5000th of an inch each in
diameter.]
The creature drawn in our fig. 50 is, then, the typical trypanosome.
It is this which the medical investigator looks for in his human
or animal patients; it is this which he has regarded as the sign
and proof of infection. Experiments have shown that, though so much
alike in appearance in the different diseases we have named, yet each
trypanosome has its own properties. Human blood-serum is poisonous
to one and not to another; an animal immune to one is not immune
to another. At present no treatment has been discovered which will
destroy the parasites when once they have effected a lodgment, or
act as an antidote to the poison which they produce in the infected
animal or man. But the fact that in some cases an animal may become
immune to the attack of the parasite which usually is deadly to its
kind, gives hope of an eventual curative treatment for trypanosome
infection; as does also the fact that the serum of some animals acts
as a poison to trypanosomes which flourish in other animals.
With regard to immunity, it must always be remembered that we are
liable to confuse two different conditions under this one term.
An animal may be said to be immune to blood-parasite because that
parasite is actually unable to live in its blood. On the other
hand an animal is often said to be immune to a parasite when the
parasite can and does flourish in its blood or tissues but produces
no poisonous effect. A more precise nomenclature would describe the
attacked organism in the first case as “repellent,” for it repels
the parasite altogether; in the second case as “tolerant,” for it
tolerates the presence and multiplication of the parasite without
suffering by it.
We have yet to learn a good deal more as to the repulsion and the
toleration of the trypanosome parasites by mammals and man. Still
more have we to learn about the life-history of the trypanosome. At
the moment of writing, absolutely nothing has been ascertained as to
the life-history of the trypanosome of mammalian blood, except that
they multiply in the blood by longitudinal fission. Our ignorance
about them is all the more serious since other trypanosomes,
discovered by Danilewesky in birds, have been studied and have been
shown to go through the most varied phases of multiplication and
change of size and shape, including a process of sexual fertilisation
like that of the malaria parasite, to which, indeed, it now seems
certain the trypanosomes are very closely allied.
It is to Dr. Schaudinn[26], that we owe a knowledge of some most
extraordinary and important facts with regard to the trypanosomes
parasitic in the blood of the little stone-owl of southern Europe
(_Athene noctua_). These facts are so remarkable that, were Dr.
Schaudinn not known as a very competent investigator of microscopic
organisms we should hesitate to accept them as true. Supposing, as
is not improbable, that similar facts can be shown in regard to the
trypanosomes of mammalian blood, the conclusions which our medical
investigators have based upon a very limited knowledge of the form
and life-history of the trypanosomes occurring in diseases such
as sleeping sickness, surra, and nagana, are likely to be gravely
modified, and practical issues of an unexpected kind will be involved.
As has already been pointed out in this article, the British
Government has no staff of public servants trained to deal with the
world-wide problems of sanitation and disease which necessarily
come with increasing frequency before the puzzled administrators
of our scattered Empire. There is no provision for the study of
the nature and history of blood-parasites in this country, that
is to say, no provision of laboratories with the very ablest and
exceptionally-gifted investigators at their head[27]. We play with
the provision of an adequate army, officers, and equipment to fight
disease, which annually destroys hundreds of thousands of our people,
much as barbarous states or bankrupt European kingdoms play with
the provision of an ordinary army and navy. Their forces exist on
paper, or even in fact, but have no ammunition, no officers, and no
information; and there is no pay for the soldiers or sailors. Dr.
Schaudinn, on the other hand, carried on his researches as an officer
of the German Imperial Health Bureau of Berlin; and the account
of them was published in the official Report of that important
department of the German imperial administrative service three years
ago.
[Illustration: FIG. 52.
_Trypanosoma Ziemanni_, from the gut of the gnat (_Culex_),
having been sucked in with the blood of the owl (_Athene
noctua_). A, fertilized vermiform stage. B, multiplication of
nucleus. C, elongation and coiling, with increase of nuclei
(_after_ Schaudinn).]
[Illustration: FIG. 53.
Minute neutral Trypanosomes in the gut of the gnat liberated from
the coiled form of Fig. 52, C (_after_ Schaudinn).]
It is not possible here to give a full report on Dr. Schaudinn’s
work; but it appears that he has studied two distinct species of
trypanosoma, both occurring side by side in the blood of the little
stone-owl, and already seen but incompletely studied, by Danilewsky
and Ziemann. The second of the two species of trypanosome is in
some respects the more remarkable. Schaudinn calls it _Trypanosoma
Ziemanni_; and from the figures which are here given (figs. 4, 5,
6, and 7), copied from his article, with the explanations below
the figures, the reader will at once see what an extraordinary
range of form and mode of multiplication is presented by this one
species of trypanosome. Space will not permit us to comment on these
various phases beyond noting how assuredly such forms would have
escaped recognition as belonging to the trypanosome history if seen,
before Dr. Schaudinn’s memoir was printed, by any of our medical
commissioners blindly exploring round about the diseases caused by
trypanosomes in man and mammals.
[Illustration: FIG. 54.
A, B, C, D, Elongated spiral forms of _Trypanosoma Ziemanni_
(some intertwined) developed from those of Fig. 53--showing
transverse division, nucleus, and blepharoplast.
E, F, pear-shaped forms resulting from the contraction of forms
like A; G, a cluster of very minute individuals.
These forms are observed in the gnat and also in the blood of
the owl, into which they pass when the gnat bites that bird, and
there give rise to the large male and female Trypanosomes seen in
Fig. 55 (_after_ Schaudinn).]
One very astonishing and revolutionary fact discovered by Schaudinn
we must, however, especially point out. Medical men have long been
acquainted with the spirillum, or spiral threads, discovered by
Obermeyer in the blood of patients suffering from the relapsing
fever of eastern Europe. These were universally and without question
regarded as Bacteria (vegetable organisms) and referred to the genus
“Spirochæta” of Ehrenberg. They were called _Spirochæta Obermeieri_;
and relapsing fever was held to be a typical case of a bacterial
infection of the blood. It is now shown by Schaudinn that the
blood-parasite spirochæta is a phase of a trypanosome (fig. 54);
that it has a large nucleus and a micronucleus or blepharoplast,
neither of which are present in the spiral Bacteria; and, further,
that it alters its shape, contracting so as to present the form
of minute oval or pear-shaped bodies, each provided with a larger
and a smaller nucleus (fig. 54, E, F). These oval bodies are often
engulfed by the colourless corpuscles (phagocytes) of the blood;
and it is in the highest degree probable that in this condition
they have been observed in some tropical diseases without their
relation to the spiral forms being suspected. The corpuscles lately
described by Leishman, in cases of a peculiar Indian fever, are
very probably of this nature, as are also similar bodies recently
described in Delhi sore. On the whole, it may safely be said that the
researches of Dr. Schaudinn, of which only a preliminary account has
yet been published, have widely modified our conceptions as to these
blood-parasites, and must lead to important discoveries in regard to
diseases caused by them in mammals and in man.
[Illustration: FIG. 55.
_Trypanosoma Ziemanni_, from the blood of the little owl. The
stages shown in Figs. 52-54 are passed inside the gnat. The
spiral and pear-shaped bodies of Fig. 54 pass from the gnat’s
proboscis into the blood of the little owl, and grow there into
the large forms here figured. A, B, and C are females, destined
to be fertilized by spermatozoa (see Fig. 21) when swallowed by
a gnat. D and E are male Trypanosomes, which will give rise each
to eight fertilizing individuals or spermatozoa as shown in Fig.
56--when swallowed by a gnat.]
The facts that wild game serve as a tolerant reservoir of
trypanosomes for the infection of domesticated animals by the
intermediary of the tsetze fly, and that native children in
malarial regions act the same part for the malarial parasite and
mosquito, suggest very strongly that some tolerant reservoir of the
sleeping-sickness trypanosome may exist in the shape of a hitherto
unsuspected mammal, bird, or insect. The investigation of that
hypothesis and the discovery of the reproductive and secondary forms
of the mammalian trypanosomes are the matters which now most urgently
call for the efforts of capable medical officers. But we must not
be sanguine of rapid progress, since men of the scientific quality
needful for pursuing these enquiries are not numerous; and those who
exist are not endowed with private fortunes, as a rule. At the same
time no attempt is made by the British Government to take such men
into its pay, or to provide for the training and selection of such
officers.[28]
[Illustration: FIG. 56.
Male _Trypanosoma Ziemanni_, giving rise by nuclear division to
eight spermatozoa or microgametes. From the stomach of the gnat
(_Culex_).
Each of these penetrates and fuses with the substance of a female
Trypanosome, swallowed at the same time or already taken in by
the gnat. The fertilized animalculæ is the vermiform motile stage
of Fig. 52, A; and so we return to the starting-point of the
cycle (_after_ Schaudinn).]
The relations of parasites to the organisms upon or in which they are
parasitic, and the relation of man, once entered on the first steps
of his career of civilisation, to the world of parasites, form one of
the most instructive and fascinating chapters of natural history. It
cannot be fully written yet, but already some of the conclusions to
which the student is led in examining this subject have far-reaching
importance and touch upon great general principles in an unexpected
manner.
Before the arrival of man--the would-be controller, the disturber
of Nature--the adjustment of living things to their surrounding
conditions and to one another has a certain appearance of perfection.
Natural selection and the survival of the fittest in the struggle
for existence lead to the production of a degree of efficiency and
harmonious interaction of the units of the living world, which,
being based on the inexorable destruction of what is inadequate and
inharmonious as soon as it appears, result in a smooth and orderly
working of the great machine, and the continuance by heredity of
efficiency and a high degree of individual perfection.
Parasites, whether microscopic or of larger size, are not, in such
circumstances, the cause of widespread disease or suffering. The
weakly members of a species may be destroyed by parasites, as others
are destroyed by beasts of prey; but the general community of the
species, thus weeded, is benefited by the operation. In the natural
world the inhabitants of areas bounded by sea, mountain, and river
become adjusted to one another; and a balance is established. The
only disturbing factors are exceptional seasons, unusual cold, wet,
or drought. Such recurrent factors may from time to time increase the
number of the weakly who are unable to cope with the invasions of
minute destructive parasites, and so reduce, even to extermination
the kinds of animals or plants especially susceptible to such
influences. But anything like the epidemic diseases of parasitic
origin with which civilised man is unhappily familiar seems to be due
either to his own restless and ignorant activity or, in his absence,
to great and probably somewhat sudden geological changes--changes of
the connexions, and therefore communications, of great land areas.
It is abundantly evident that animals or plants which have, by
long æons of selection and adaptation, become adjusted to the
parasites and the climatic conditions and the general company (so
to speak) of one continent may be totally unfit to cope with those
of another; just as the Martian giants of Mr. H. G. Wells, though
marvels of offensive and defensive development, were helpless in
the presence of mundane putrefactive bacteria and were rapidly and
surely destroyed by them. Accordingly, it is not improbable that such
geological changes as the junction of the North and South American
continents, of North and South Africa, and of various large islands
and neighbouring continents, have, in ages before the advent of
man, led to the development of disastrous epidemics. It is not a
far-fetched hypothesis that the disappearance of the whole equine
race from the American continent just before or coincidently with
the advent of man--a region where horses of all kinds had existed in
greater variety than in any other part of the world--is due to the
sudden introduction, by means of some geological change, of a deadly
parasite which spread as an epidemic and extinguished the entire
horse population.
Whatever may have happened in past geological epochs, by force of
great earth-movements which rapidly brought the adaptations of one
continent into contact with the parasites of another, it is quite
certain that man, proud man, ever since he has learnt to build
a ship, and even before that, when he made up his mind to march
aimlessly across continents till he could go no further, has played
havoc with himself and all sorts of his fellow-beings by mixing up
the products of one area with those of another. Nowhere has man
allowed himself--let alone other animals or even plants--to exist in
fixed local conditions to which he or they have become adjusted. With
ceaseless restlessness he has introduced men and beasts and plants
from one land to another. He has constantly migrated with his herds
and his horses, from continent to continent. Parasites, in themselves
beneficent purifiers of the race, have been thus converted into
terrible scourges and the agents of disease. Europeans are decimated
by the locally innocuous parasites of Africa; the South Sea islanders
are exterminated by the comparatively harmless measles of Europe.
A striking example of the disasters brought about by man’s blind
dealings with Nature--disasters which can and will hereafter be
avoided by the aid of science--is to be found in the history of
the insect phylloxera and the vine. In America the vine had become
adjusted to the phylloxera larvae, so that when they nibbled its
roots the American vine threw out new root-shoots and was none the
worse for the little visitor. Man in his blundering way introduced
the American vine, and with it the phylloxera, to Europe; and in
three years half the vines in France and Italy were destroyed by
the phylloxera, because the European vines had not been bred in
association with this little pest, and had not acquired the simple
adjusting faculty of throwing out new shoots.
But it is not only by his reckless mixing up of incompatibles from
all parts of the globe that the unscientific man has risked the
conversion of paradise into a desert. In his greedy efforts to
produce large quantities of animals and plants convenient for his
purposes, and in his eagerness to mass and organise his own race for
defence and conquest, man has accumulated unnatural swarms of one
species in field and ranch and unnatural crowds of his own kind in
towns and fortresses. Such undiluted masses of one organism serve as
a ready field for the propagation of previously rare and unimportant
parasites from individual to individual. Human epidemic diseases as
well as those of cattle and crops, are largely due to this unguarded
action of the unscientific man.
A good instance of this is seen in the history of the coffee
plantations of Ceylon, where a previously rare and obscure parasitic
fungus, leading an uneventful life in the tropical forests of that
country, suddenly found itself provided with an unlimited field
of growth and exuberance in the coffee plantations. The coffee
plantations were destroyed by this parasite, which has now returned
to its pristine obscurity. Disharmonious, blundering man was
responsible for its brief triumph and celebrity. Dame Nature had not
allowed the coffee fungus more than a very moderate scope. Man comes
in and takes the reins; disaster follows; and there is no possibility
of return to the old régime. Man must make his blunders and retrieve
them by further interference--by the full use of his intelligence, by
the continually increasing ingenuity of his control of the physical
world, which he has ventured to wrest from the old rule of natural
selection and adaptation.
The adjustment of all living things to their proper environment
is one of great delicacy and often of surprising limitation. In
no living things is this more remarkable than in parasites. The
relation of a parasite to the “host” or “hosts” in which it can
flourish (often the host is only one special species or even variety
of plant or animal) is illustrated by the more familiar restriction
of certain plants to a particular soil. Thus the Cornish heath only
grows on soil overlying the chemically peculiar serpentine rocks
of Cornwall. The two common parasitic tape-worms of man pass their
early life the one in the pig and the other in bovine animals. But
that which requires the pig as its first host (_Tænia solium_) cannot
use a bovine animal as a substitute; nor can the other (_Tænia
mediocanellata_) exist in a pig. Yet the difference of porcine and
bovine flesh and juices is not a very patent one; it is one of small
variations in highly complex organic chemical substances. A big
earth-worm-like stomach-worm flourishes in man, and another kind
similar to it in the horse. But that frequenting man cannot exist in
the horse, nor that of the horse in man. Simpler parasites, such as
are the moulds, bacteria, and again the blood-parasites, trypanosoma,
etc., exhibit absolute restrictions as to the hosts in which they can
or can not flourish without showing specific changes in their vital
processes. Being far simpler in structure than the parasitic worms,
they have less “mechanism” at their disposal for bringing about
adjustment to varied conditions of life. The microscopic parasites
do not submit to alterations in the chemical character of their
surroundings without themselves reacting and showing changed chemical
activities. A change of soil (that is to say of host) may destroy
them; but, on the other hand, it may lead to increased vigour and the
most unexpected reaction on their part in the production of virulent
chemical poisons.
We are justified in believing that until man introduced his
artificially selected and transported breeds of cattle and horses
into Africa there was no nagana disease. The _Trypanosoma Brucei_
lived in the blood of the big game in perfect harmony with its
host. So, too, it is probable that the sleeping-sickness parasite
flourished innocently in a state of adjustment due to tolerance on
the part of the aboriginal men and animals of West Africa. It was not
until the Arab slave raiders, European explorers, and indiarubber
thieves stirred up the quiet populations of Central Africa, and mixed
by their violence the susceptible with the tolerant races, that the
sleeping-sickness parasite became a deadly scourge--a “disharmony” to
use the suggestive term introduced by my friend Elias Metschnikow.
The adjustment of primaeval populations to their conditions has also
been broken down by “disharmonies” of another kind, due to man’s
restless invention, as explained a few years ago in the interesting
book of Mr. Archdall Reid on the “Present Evolution of Man.” Not
only does the human race within given areas become adjusted to a
variety of local parasites, but it acquires a tolerance of dangerous
drugs, such as alcohol and opium, extracted by man’s ingenuity from
materials upon which he operates. A race thus provided and thus
immune imposes, by its restless migrations, on unaccustomed races the
deadly poisons to the consumption of which it is itself habituated.
The unaccustomed races are deteriorated or even exterminated by the
poisons thus introduced.
Infectious disease, it was long ago pointed out, must be studied
from three main points of view: (1) the life history and nature
of the disease-germ or infective matter; (2) the infected subject,
his repellant or tolerant possibilities, and his predisposition or
receptivity; (3) the intermediary or carrying agents. Whilst it is
true that little or nothing has been done by the State in acquiring
or making use of knowledge as to the first and second of these
factors, with a view to controlling the spread of disease, it is
the fact that much has been done both in the way of investigation
and administration in relation to the third factor. The great
public-health enquiries and consequent legislation in this country,
in which scientific men of the highest qualifications, such as
Simon, Farr, Chadwick, and Parkes, took part during the Victorian
period, have had excellent results; to them are due the vast
expenditure at the present day on pure water, sewage disposal, and
sanitary inspection. But little or nothing has been done in regard
to the first and second divisions of the subject, in which the less
organised portions of the British Empire are more deeply concerned
than in waterworks and sewer-pipes. It is still contested whether
leprosy (which is a serious scourge in the British Empire, though
expelled from our own islands) is a matter of predisposition caused
by diet or solely due to contagion; and yet it is left to individual
practitioners to work out the problem. The State prepares vaccine
lymph in a cheap and unsatisfactory way for the use of its, till
recently, compulsorily vaccinated citizens; but the State, though
thus interfering in the matter of vaccine, has spent no money to
study effectively and so to improve the system of vaccination. Here
and there some temporary and ineffective enquiry has been subsidised
by a Government office; but there is no great army of investigators
working in the best possible laboratories, led by the ablest minds
of the day, with the constant object of improving and developing in
new directions the system of inoculation. Surely if compulsion, or
every pressure short of compulsion, is justified in enforcing vaccine
inoculation on every British family, it would be only reasonable and
consistent to expend a million or so a year in the perfection and
intelligent control of this remedy by the most skilled investigators.
Yet not a halfpenny is spent by the British Government in this way.
Medicine is organised in this country by its practitioners as a
fee-paid profession; but as a necessary and invaluable branch of
the public service it is neglected, misunderstood, and rendered to
a large extent futile by inadequate funds and consequent lack of
capable leaders. The defiant desperate battle which civilised man
wages with Nature must go on; but man’s suffering and loss in the
struggle--the delay in his ultimate triumph--depend solely on how
much or how little the great civilised communities of the world seek
for increased knowledge of nature as the basis of their practical
administration and government.
POSTSCRIPT, December, 1906.--Messrs. Thomas and Breinl, of the
Liverpool School of Tropical Medicine, two years ago discovered
and published the fact that an arsenical aniline product known as
“atoxyl” when injected into patients suffering from Sleeping Sickness
destroys the parasite and promises to be a cure for this terrible
infection. Experiments are in progress in many quarters in regard to
this treatment, but certainty can only be arrived at by prolonged
observation of the patients. The newspapers have lately, in error,
attributed this discovery to Dr. Robert Koch of Berlin, who has
merely confirmed the observations of the earlier workers.--E. R. L.
FOOTNOTES:
[1] The foundation of the Royal Society of London is most intimately
connected with the University of Oxford. Dr. Wallis, an original
member, writes:--‘I take its first ground and foundation to have
been in London about the year 1645, when Dr. Wilkins and others met
weekly at a certain day and hour.... About the year 1648-9 some of
our company were removed to Oxford; first Dr. Wilkins, then I, and
soon after Dr. Goddard. Those in London continued to meet there as
before (and we with them, when we had occasion to be there), and
those of us at Oxford; with Dr. Ward (since Bishop of Salisbury),
Dr. Ralph Bathurst (now President of Trinity College in Oxford),
Dr. Petty (since Sir William Petty), Dr. Willis (then an eminent
physician in Oxford), and divers others, continued such meetings in
Oxford and brought those studies into fashion there; meetings first
at Dr. Petty’s lodgings (in an apothecarie’s house) because of the
convenience of inspecting drugs and the like, as there was occasion;
and after his remove to Ireland (though not so constantly) at the
lodgings of Dr. Wilkins, then Warden of Wadham College, and after
his removal to Trinity College in Cambridge, at the lodgings of
the Honourable Mr. Robert Boyle, then resident for divers years in
Oxford.... In the meanwhile our company at Gresham College being much
again increased by the accession of divers eminent and noble persons,
upon his Majesty’s return, we were (about the beginning of the year
1662) by his Majesty’s grace and favour incorporated by the name of
the Royal Society.’
[2] See, however, the letter from the _Times_, reprinted on p. 62.
[3] There is a tendency among writers on Variation, as affording
the opportunity for the operation of Natural Selection, to assume
that the variations presented by organisms are minute variations in
every direction around a central point. Those observers who have done
useful work in showing the definite and limited character of organic
variations have very generally assumed that they are opposing a
commonly held opinion that variation is of this equally distributed
character. I cannot find that Mr. Darwin made any such assumption;
and it is certain, and must on reflection have been recognized by all
naturalists, that the variations by the selection and intensification
of which natural selection has produced distinct forms or species,
and in the course of time altogether new groups of plants and
animals, are strictly limited to definite lines rendered possible,
and alone possible, by the constitution of the living matter of the
parental organism. We have no reason to suppose that the offspring
of a beetle could in the course of any number of generations present
variations on which selection could operate so as to eventually
produce a mammalian vertebrate; or that, in fact, the general result
of the process of selection of favourable variations in the past
has not been _ab initio_ limited by the definite and restricted
possibilities characteristic of the living substance of the parental
organisms of each divergent line or branch of the pedigree.
[4] See p. 62.
[5] M. Paul Bourget of the Académie Française, is not only a charming
writer of modern ‘novels,’ but claims to be a ‘psychologist,’ a title
which perhaps may be conceded to every author who writes of human
character. His works are so deservedly esteemed, and his erudition
is as a rule, so unassailable, that in selecting him as an example
of the frequent misrepresentation, among literary men, of Darwin’s
doctrine, I trust that my choice may be regarded as a testimony of
my admiration for his art. In his novel _Un Divorce_, published in
1904, M. Bourget, says: ‘La lutte entre les espèces, cette inflexible
loi de l’univers animal, a sa correspondance exacte dans le monde
des idées. Certaines mentalités constituent de véritables espèces
intellectuelles qui ne peuvent pas durer à côté les unes des autres’
(Edition Plon, p. 317). This inflexible law of the animal universe,
the struggle between species, is one which is quite unknown to
zoologists. The ‘struggle for existence,’ to which Darwin assigned
importance, is not a struggle between different species, but one
between closely similar _members of the same species_. The struggle
between species is by no means universal, but in fact very rare. The
preying of one species on another is a moderated affair of balance
and adjustment which may be described rather as an accommodation than
as a struggle.
A more objectionable misinterpretation of the naturalists’ doctrine
of the survival of the fittest in the struggle for existence is that
made by journalists and literary politicians, who declare, according
to their political bias, either that science rightly teaches that
the gross quality measured by wealth and strength alone can survive
and should therefore alone be cultivated, or that science (and
especially Darwinism) has done serious injury to the progress of
mankind by authorizing this teaching. Both are wrong, and owe their
error to self-satisfied flippancy and traditional ignorance in
regard to nature-knowledge and the teaching of Darwin. The ‘fittest’
does not mean the ‘strongest.’ The causes of survival under Natural
Selection are very far indeed from being rightly described as mere
strength, nor are they baldly similar to the power of accumulating
wealth. Frequently in Nature the more obscure and feeble survive
in the struggle because of their modesty and suitability to given
conditions, whilst the rich are sent empty away and the mighty perish
by hunger.
[6] A short discussion of this subject and the introduction of the
term ‘educability’ was published in a paper by me entitled ‘The
Significance of the Increased Size of the Cerebrum in recent as
compared with extinct Mammalia,’ Cinquantenaire de la Société de
Biologie, Paris, 1899, pp. 48-51.
It has been pointed out to me by my friend Dr. Andrews, of the
Geological Department of the British Museum, that the brain cavity
of the elephants was already of relatively large size in the Eocene
members of that group, which may be connected with the persistence of
these animals through subsequent geological periods.
[7] It would be an error to maintain that the process of Natural
Selection is entirely in abeyance in regard to Man. In an interesting
book, _The Present Evolution of Man_, Dr. Archdall Reid has shown
that in regard to zymotic diseases, and also in regard to the use of
dangerous drugs such as alcohol and opium, there is first of all the
acquirement of immunity by powerful races of men through the survival
among them of those strains tolerant of the disease or of the drug,
and secondly, the introduction of those diseases and drugs by the
powerful immune race, in its migrations, to races not previously
exposed either to the diseases or the drugs, and a consequent
destruction of the invaded race. The survival of the fittest is, in
these cases, a survival of the tolerant and eventually of the immune.
[8] ‘Religion means the knowledge of our destiny and of the means
of fulfilling it.’--_Life and Letters of Mandell Creighton sometime
Bishop of London_, vol. ii. p. 195.
[9] This has been established in the case of the _Trypanosoma
Brucei_, a minute parasite living in the blood of big game
in south-east Africa, amongst which it is disseminated by a
blood-sucking fly, the _Glossina morsitans_ or Tsetze fly. The
parasite appears to do little or no harm to the native big game, but
causes a deadly disease both in the horses and cattle introduced by
Europeans and in the more anciently introduced native cattle (of
Indian origin). Similar cases are found where a disease germ (such
as that of measles) produces but a small degree of sickness and
mortality in a population long associated with it, but is deadly to
a human community to which it is a new-comer. Thus Europeans have
introduced measles with deadly results in the South Sea Islands. A
similar kind of difficulty, of which many might be cited, is brought
about by man’s importations and exportations of useful plants. He
thus brought the Phylloxera to Europe, not realizing before hand
that this little parasitic bug, though harmless to the American
vine, which puts out new shoots on its roots when the insect injures
the old ones, is absolutely deadly to the European vine, which
has not acquired the simple but all-important mode of growth by
which the American vine is rendered safe. Thus, too, he took the
coffee-plant to Ceylon, and found his plantations suddenly devastated
by a minute mould, the _Himileia vastatrix_, which had lived very
innocently before that in the Cingalese forests, but was ready to
burst into rapacious and destructive activity when the new unadjusted
coffee-trees were imported by man and presented in carefully crowded
plantations to its unrestrained infection.
[10] The phosphorescent disease of the sand-hopper (_Talitrus_) is
described by Giard and Billet in a paper entitled ‘Observations
sur la maladie phosphorescente des Talitres et autres Crustacés,’
in the memoirs of the Société de Biologie, Oct. 19, 1889. Billet
subsequently gave a further account of this organism, and named
it _Bacillus Giardi_--after Professor Giard of Paris. (Bulletins
scientifiques de la France et de la Belgique, xxi. 1898, p. 144).
It appears that the parasite is transmitted from one individual to
another in coition. The specimens studied by Giard and Billet were
obtained at Wimereux near Boulogne. I found the disease very abundant
at Ouistreham near Caen in the summer of 1900. I have not observed
it nor heard of its occurrence on the English coast. Sea-water
commonly contains a free-living phosphorescent bacterium which can
be cultivated in flasks of liquid food so as to give rich growths
which glow like a lamp when the flask is agitated so as to expose the
contents to oxidation. This bacterium is not, however, the cause of
the ‘phosphorescence’ of the sea often seen on our coasts. That is
due in most cases to a much larger organism, as big as a small pin’s
head, and known as _Noctiluca miliaris_.
[11] As little is the question of the use and abuse of food and drink
dealt with, as yet, by civilized man. As in many other matters man
has carried into his later crowded, artificial, nature-controlling
life habits and tendencies derived from savage prehistoric days, so
has he perpetuated ways of feeding which are mere traditions from his
early ‘animal’ days, and have never been seriously called in question
and put to proof. The persistence under new conditions of either
habit or structure which belonged to old conditions may be attended
with great danger and difficulty to an organism which changes, as
man does, with great rapidity important features in its general
surroundings and mode of life. This is in effect Metschnikoff’s
doctrine of ‘désharmonies.’ It is probable that in very early days
when a tribe of primitive men killed a mammoth, they all rushed on
to the dead monster and gorged as much of its flesh as they could
swallow (cooked or possibly uncooked). They had to take in enough to
last for another week or two--that is to say, until another large
animal should be trapped and slain. Accordingly he who could eat most
would be strongest and best able to seize a good share when the next
opportunity arrived, and it naturally became considered an indication
of strength, vigour, and future prosperity to be capable of gorging
large quantities of food. By means of the phrases ‘enjoying a good
appetite,’ or ‘a good trencherman,’ or other such approving terms,
civilized society still encourages the heavy feeder. The lower
classes always consider a ravenous appetite to be an indication of
strength and future prosperity in a child. Most healthy men, and
even many women, in Western Europe, attack their food and swallow
it without sufficient mastication, and as though they did not hope
to get another chance of feeding for a week or two to come. Medical
men have never ventured to investigate seriously whether civilized
man is doing best for his health in behaving like a savage about
his food. It is their business to attend to the patient with a
disordered digestion, but not to experiment upon the amount of food
of various kinds which the modern man should swallow in order to
avoid indigestion and yet supply his alimentary needs. No individual
can possibly pay medical men to make these observations. It is the
business of the State to do so, because such knowledge is not only
needed by the private citizen, but is of enormous importance in the
management of armies and navies, in the victualling of hospitals,
asylums, and prisons. Thousands of tons of preserved meat have been
wasted in recent wars because the reckless and ignorant persons who
purchased the preserved meat to feed soldiers had never taken the
trouble to ascertain whether preserved meat can be eaten by a body of
men as a regular and chief article of diet. It appears that certain
methods of preserving meat render it innutritious and impossible as
a diet.
It is probable from recent experiment that we all, except those
unfortunate few who do not get enough, eat about twice as much
as we require, and that the superfluous quantity swallowed not
only is wasted, but is actually a cause of serious illness and
suffering. It surely is an urgent matter that these questions about
food should be thoroughly investigated and settled. In the opinion
of the most eminent physiologist of the United States (Professor
Bowditch), we shall never establish a rational and healthy mode of
feeding ourselves until we give up the barbarous but to some persons
pleasant custom of converting the meal into a social function; we
are thus tempted into excess. Only long and extensive experiment
can provide us with definite and conclusive information on this
matter, which is far more important than, at first sight, it seems
to be. And similarly with regard to the admittedly serious question
of alcohol--only very extensive and authoritative experiment will
suffice to show mankind whether it is a wise and healthy thing to
take it in small quantities, the exact limits of which must be
stated, or to reject it altogether.
[12] It is, perhaps, needful to point out that what is aimed at is
that the education of all the youth of the country, both of pass-men
and of class-men, of girls as well as of boys, of the rich as
well as of the poor, should be primarily directed to imparting an
acquaintance with what we already possess in respect of knowledge
of Nature, and the training of the pupil so as to enable him or
her (_a_) to make use of that knowledge, and (_b_) to take part
in gaining new knowledge of Nature, at this moment needed but
non-existent. This does not involve the complete exclusion of other
subjects of instruction, to which about one-third of the time and
effort of school and college life might be devoted.
[13] I desire especially to draw the attention of those who have
misunderstood and misrepresented my estimate of the importance of the
study of History, to this paragraph.--E.R.L.
[14] The practical steps which would correspond to the views
enunciated in this discourse are two. First, the formation of an
educational association to establish one or more schools and colleges
in which nature-knowledge and training in nature-searching should
be the chief matters to which attention would be given, whilst
reasonable methods would also be employed for implanting in the
minds of the students a love and understanding of literature and
other forms or art. Those who desired such an education for their
children would support these schools and colleges, just as in the
days of Anglican exclusiveness the Nonconformists and Roman Catholics
supported independent educational institutions. The second practical
step would be the formation of a political union which would make due
respect to efficiency, that is to say, to a knowledge of Nature, a
test question in all political contests. No candidate for Parliament
would receive the votes of the union unless he were either himself
educated in a knowledge of Nature or promised his support exclusively
to ministers who would insist on the utilization of nature-knowledge
in the administration of the great departments of State, and would
take active measures of a financial character to develop with far
greater rapidity and certainty than is at present the case, that
inquiry into and control of Nature which is the indispensable factor
in human welfare and progress. Such a programme will, I hope,
at no distant date obtain the support of a sufficient number of
parliamentary voters to raise political questions of a more genuine
and interesting character than those which many find so tedious at
the present moment.
[15] It seems necessary to emphasize that I here say merely that
no “new support” is given to the notion of so-called telepathy, a
support some persons have wrongly claimed. I do not say that the
notion is rendered less likely to prove true than it was before.
[16] See the introduction to Part II. of a Treatise on Zoology.
Edited by E. Ray Lankester (London: A. & C. Black).
[17] From the Jubilee volume of the Soc. de Biol. of Paris, 1899.
Reprinted in _Nature_, vol. lxi., 1900, pp. 624, 625.
[18] I use the term ‘acquired’ without prejudice in the sense given
to that word by Lamarck himself. It is of primary importance that
those who follow this controversy should clearly understand what
Lamarck pointed to by this word ‘acquired.’ Utter confusion and
absurdity has resulted from a misunderstanding on this subject
by some writers who deliberately call newly appearing congenital
characters ‘acquired’ or ‘acquisitions.’
[19] _Nature_, vol. li., 1894, p. 127.
[20] In a review of Metschnikoff’s ‘Leçons sur l’Inflammation’ in
_Nature_, 1899.
[21] See the next chapter, devoted to this subject.
[22] I had the honour and good fortune to found this association and
to collect the funds so generously given to it--then for many years
to act as its honorary secretary, to design and superintend the
erection of the laboratory and to organize, in conjunction with my
scientific colleagues, its staff, its scheme of work and government.
On the death of our beloved president, Professor Huxley, I was
elected as his successor, and still occupy that position.
[23] The disease has actually entered into the administrative area
known as British East Africa, but has not made any rapid progress
towards the coast. According to a report by Dr. Wiggins, the disease
is confined in British East Africa, as in Uganda, to those areas in
which _Glossina palpalis_ occurs.
[24] Only last year (1905) Lieut. Tulloch, of the Army Medical
Department, who with Professor Minchin was engaged in carrying on
further researches for the Royal Society on the sleeping sickness
at Entebbe in Uganda, became infected by the trypanosome, probably
through an unobserved bite by a tsetze fly, and died of the disease
soon after his return to England.
[25] Professor Minchin investigated this subject during 1905 in
Uganda whither he went on behalf of the Tropical Diseases Committee
of the Royal Society. He did not discover anything corresponding
to the development of the malarial parasite in the gnat, but his
investigations are not yet brought to a conclusion (December, 1906).
[26] Dr. Schaudinn died in 1906. He was only 35 years of age.
[27] Since this was written a professorship of Protozoology has
with the assistance of the Colonial Office been established in the
University of London. This is a first step towards a recognition of
the duty of the State in this matter.
[28] See footnote on p. 179.
* * * * * *
Transcriber’s note:
The repeated caption heading ‘Fig. x.’ has been removed in Figures
1, 2, 3, 4, 10, 12 and 44.
Obvious typographical errors and punctuation errors have been
corrected after careful comparison with other occurrences within
the text and consultation of external sources.
Except for those changes noted below, all misspellings in the text,
and inconsistent or archaic usage, have been retained: for example,
sleeping sickness, sleeping-sickness; kosmos; acquirement; employés;
imbibition.
Pg 84 (Fig. 11): ‘at 3186 (Soddy)’ replaced by ‘at 318·6 (Soddy)’.
Pg 91 (Fig. 12): ‘the line A A)’ replaced by ‘the line A A,’.
Pg 95: ‘Brunettière and his’ replaced by ‘Brunetière and his’.
Pg 146 (Fig. 46): ‘T. Brucii’ replaced by ‘T. Brucei’.
Pg 148: ‘Spirocheta pallida’ replaced by ‘Spirochæta pallida’.
Pg 149: ‘of the commuity,’ replaced by ‘of the community,’.
Pg 177: ‘miscroscopic animals’ replaced by ‘microscopic animals’.