THE
MEDICAL EXAMINER,
AND
RECORD OF MEDICAL SCIENCE. .
NEW SERIES.—NO. L X V III.—A U GU S T, 1 8 50.
ORIGINAL COMMUNICATIONS.
On Acclimation, Jin Inaugural Essay presented for the Degree
of Doctor of Medicine in the University of Pennsylvania. By
Philip C. Williams, M. D., of Winchester, Virginia.
Acclimation—the result of the various modifications in the
human system, when it is subjected to the influence of a climate
different from that to which it has been accustomed—is a theme
of deep interest.
It is one, the proper appreciation of which would prevent or
greatly mitigate many of the diseases to which man is now sub-
jected, in his migrations for the sake of travel, commerce, and the
pursuit of science. The question assumes still greater importance
when viewed in its relation to colonization, or the settlement of
large bodies of men in regions where the climate is often so dif-
ferent from that of their own native land. Within the limits of the
United States alone, the changes thus effected by the continual
movement of the people, from the old to the new States and terri-
tories, invest the problem with a peculiar and home interest.
It seems to be an established law of nature, that the constitution
of man must be modified by the atmospheric influences with which
he is surrounded, and that it must carry the impress of the climate
which he inhabits.
While we admit the difficulty of accounting for all the distinct-
ive traits that characterize the chief races of mankind, we cannot
deny that many of the modifications in their external appearance,
and physiological actions, are attributable to the influence of cli-
mate. Did the narrow limits of an inaugural essay permit, I
might, to substantiate this view, repeat the affirmative opinions of
Hippocrates, Montesquieu, and Cabanis. The “ Father of Medi-
cine ” was the first to point out the controlling influence of cli-
mate, as he did so clearly in his essay on “ Waters, Airs, and
Places,” when he compared the people of Europe with those of
Asia, and attributed the superiority of the former over the latter,
to a purer and cooler atmosphere. Montesquieu appeals to history
to show that, in the various struggles among rival candidates for
imperial sway at Rome, he who secured the assistance of the
European legions was sure of success. General history, in its
narratives of the overthrow of empires, kingdoms, and nations,
points to the same conclusion.
There are many circumstances which combine to produce
these modifications of climate, and these changes in the human
system ; such as the thermometric and hygrometric states of the
atmosphere ; the elevation above the level of the sea ; the preva-
lence of, and the exposure to, particular winds, &c.
Let us, for a moment, examine the first of these, viz., the effects
of temperature. The range of temperature compatible with human
existence is exceedingly extensive ; for we find man inhabiting not
only the hot burning plains of the tropics, but the frozen dreary
and desolate regions of the poles. The experiments of Tillet,
Fordyce, Delaroche, Blagden, Berger, &c., show that for a short
time, man is capable of enduring a temperature far surpassing that
ever reached at the hottest part of the earth’s surface. In these
experiments air heated even to 325° Fahr, was breathed, for some
minutes, without any great inconvenience. The immediate effects
were, a considerable increase in the rapidity of the pulse, and
excessive perspiration, accompanied by considerable fatigue.
On the other hand, man can live for months (as they, for ex-
ample, who have passed a winter in the polar regions,) in an air
so cold as to freeze mercury.
It has been clearly shown that the effects of heat are manifested
both upon the organic and the animal functions. On the former,
they are seen in the increased activity of the circulatory and respi-
ratory functions ; on the latter, they are followed by sensations of
languor and fatigue.
The functional effects of heat are most distinctly marked
upon the skin and the liver. The skin becomes changed in its
appearance; and assumes either a dark or a yellow tinge, which may
be attributed to an increase of the biliary secretion. The liver is
stimulated to greater activity; the secretion of bile is greatly aug-
mented, and its sensible properties are considerably changed. This
high degree of functional excitement is frequently attended with
inflammation of the organ.
The close relation observed between the skin and the liver, both
in its physiological and pathological conditions, have induced some
authors to speak of a “ cutaneo-hepatic sympathy.” {Johnson on
Tropical Climates.) But while the skin and liver are thus excited
by high and long continued atmospheric heat, the lungs and
kidneys act with diminished energy.
Cold, in its primary effects, is in direct contrast with heat. The
first is as decidedly sedative as the last is stimulating. Cold, con-
tinued for a length of time, diminishes the activity of all the func-
tions, and reduces the being exposed to its influence, to a state
resembling the sleep of hybernating animals. If continued still
longer, it produces a state much resembling intoxication, followed
by an excessive and overwhelming drowsiness, which is frequently
the prelude to a sleep that terminates in death.
Equally contrasted are the secondary effects of heat and cold, if
neither be carried so far as to derange the functions. Thus, while
the excitement of heat is followed by languor and debility, the
temporary depression from cold is succeeded by reaction, and a
feeling of increased vigor. Cold, then, when moderate in degree,
favors the activity both of the organic and animal functions—
especially respiration, circulation, and nutrition—and it is fol-
lowed by an increased development of animal heat.
This is not the place, nor have I time to dwell upon calorifica-
tion. It is sufficient to make the statement, which is satisfactorily
sustained by facts, that it can be referred to the action of no single
organ, but is the result of a chemico-vital action, going on in
every part of the system, by the combination of oxygen, taken in
through the lungs, with the different tissues of the economy. It
may be looked upon as the combustion of all the solid and fluid
elements of the body. Hence every thing, such as good nutrition,
regular respiration and circulation, that tends to increase the fuel,
increases to a correspondent degree the development of animal
heat. In speaking of cold as contributing to the development of
animal heat, it is important to remember that it operates in an in-
direct manner, viz., 1st. By condensing the atmosphere, and thus
furnishing for respiration a larger proportion of oxygen in a given
time. 2d. By exciting to exercise, in order to resist the depressing
influence of cold—thus increasing the circulation and respiration.
3d. By increasing the appetite for nutritive food—especially fatty
matters—thus affording a larger amount of “ heat generating
material.”
The direct operation of cold is to diminish the animal heat ;
and if continued in a great degree for a length of time, it may arrest
its development by inducing a torpor of the nervous system, and
thus enfeeble both the respiration and the circulation. The direct
operation of heat, on the other hand, is not only to excite the
functions generally, but also to increase the animal heat.
In estimating the influence of temperature upon the human
frame, we should study its comparative effects, for we find the
same climate producing totally different impressions upon its in-
habitants, according to their race and prior climatic habits.
This is most strikingly exhibited in the following example from
Andral, {Diet, de Med. et de Chir. pratique, art. Acclimatement.')
He states that the middle and higher portions of the island of
Ceylon are inhabited by Europeans and negroes: the former, being
exposed to a climate much hotter than that to which they were ac-
customed, die, in great numbers, of dysentery or hepatitis ; while
the latter, subjected to more cold than in their native climate, are
rapidly carried off by pneumonia or phthisis.
Another element going to make up the complex problem of
climate, is the hygrometric state of the atmosphere. This causes
modifications in the human system, evinced by a striking dif-
ference in the external appearance, muscular development, activity,
&c., of the inhabitants of a dry and hot, compared with those of
a moist and sultry climate. For instance, the inhabitants of the
sandy plains and deserts of Arabia and Africa, are thin and spare,
but active : while those of the lower and moister countries as
about the Nile, Niger, &c., exhibit large and gross frames, with a
development of adipose and cellular tissue. These differences
did not escape the attention of Hippocrates. In the valuable
treatise already referred to, he describes the inhabitants of the
Phasis, whose country is fenny, warm, humid, and wooded, and
where copious and excessive rains occur at all seasons. “ They
drink the hot and stagnant waters both when rendered putrid by
the sun and when swollen by the rains. The Phasis is the most
stagnant of all rivers, and runs the smoothest ; all the fruits which
spring there are unwholesome, of feeble and imperfect growth,
owing to the redundance of water, and on this account they do not
ripen, for much vapor from the waters overspreads the country.
For these reasons the Phasians have shapes different from those
of all othermen ; for they are large in stature, and of a very gross
habit of body, so that not a joint or vein is visible; in color they
are sallow, as if affected with jaundice.” They are naturally
languid in supporting bodily fatigue. (Vol. 1, p. 209, Adams’
edition for the Sydenham Society.)
Climate is also greatly modified by the elevation of a country
above the level of the sea. The differences thus produced are very
striking. In Mexico, for example, we have every variety of
climate. Commencing with the low lands about Vera Cruz,
which give origin to tropical fruits and tropical diseases, we
gradually rise from district to district, with its diminished tempe-
rature, till we reach the city of Mexico, around which we find the
temperature and productions of northern Europe. So with the
regions of the Andes: travelling from the countries at their base,
immediately under the Equator, we have variations from the scorch-
ing heat of a tropical sun, to the perpetual snows of Polar regions.
In all these elevated situations the atmospheric pressure is of
course lessened. Hence we find that they give rise to an accelera-
tion of the circulation, a tendency to pulmonary congestions,
dyspnoea, and even to hemorrhages, in persons accustomed to in-
habit situations nearer the level of the sea. In addition to the
rarefaction of the air, these places are subjected to great and
sudden changes of temperature, to excessively cold and violent
winds, to the accumulation of dense fogs, &c.; and thus they
exert upon the human frame many of the deleterious effects of
Polar regions.
For a full, beautiful and satisfactory exposition of these effects,
see “ Traite d’ Hygiene Publique et Privee, par Michel Levy.”
Tome 1, p. 367-380.
We next approach to a consideration of those climatic changes
effected by the exposure of a country to particular winds. This
also claimed the observation and attention of Hippocrates.
In the case of the Phasis, already alluded to, he particularly
ascribes many of the peculiarities of its climate to the long con-
tinued effects of warm, southern winds. So, also, in a subsequent
part of the same treatise, (p. 220,) when describing the different
people of Europe, he says, “ Such as inhabit a country which
is mountainous, rugged and elevated, are naturally of an enterpris-
ing, warlike disposition, and have no litttle of the savage and
ferocious in their nature.” On the other hand he remarks, “ Such
as dwell in places which are low-lying, abounding in meadows,
and ill ventilated, and who have a larger proportion of hot, than
ol cold winds, and who make use of warm w’aters—these are not
likely to be of large stature, nor well proportioned, but of a broad
make, fleshy,” &c. “ Courage and laborious enterprise are not
naturally in them.” With the region last described, is contrasted
that inhabited by the Scythians, which Hippocrates (p. 213) tells
us, “ lies under the northern bears ; and consists of plains, high-
lying and naked, and not crowned by mountains.” “ The winds
blowing from the hot regions of the earth do not reach them, or
but seldom, and wdth little force ; but the winds from the north
always blow, congealed as they are, by the snow, the ice and
much water.”
The same description equally applies to the Tartars, &c., of
Northern Asia, who inhabit a country which descends from the
Himalayah mountains to the North Sea. How striking the con-
trast between the inhabitants of this region and those upon the
southern declivity, running down to the Indian ocean, and of
course exposed to the warm winds of the south.
Differences of nearly equal importance are observed between
countries continually exposed to eastern, and those exposed to
western winds.
The nature of the soil, the qualities of the water drunk by the
inhabitants, and the extent of wooded lands, are also features not
to be overlooked in our estimate of climate.
It must be quite clear, even from this necessarily brief and im-
perfect sketch, that mere temperature, or the degree of heat
or of cold, can convey but a very inadequate idea of the
character of the seasons and climate of a country. Nor, in
estimating even the temperature of any region, can we
trust alone to its latitude, or its distance from the equator;
for the enquiries of Humboldt and others, clearly show, that the
44 Isothermal lines ” do not correspond with those of latitude, nor
are they parallel to each other. Nor are the “ Isotheral lines,”
or those of equal summer, parallel to the 44 Isocheimal lines,” or
those of equal winter ; nor either of these with the “ Isothermal
lines.” A forcible illustration of this fact is presented in the close
resemblance of the winter climate of parts of Devon and Cornwall,
in England, to that of central Italy, although they are separated
by several degrees of latitude, and differ so much in their sum-
mers.
[As a still more striking exemplification of this truth, I would
ask attention to the following extract from a speech delivered by
Mr. Benton, in the United States Senate. Speaking of the climate
of New Mexico, he says, 44 Humboldt thus describes it: 4 New
Mexico, though placed under the same latitude with Syria and
Central Persia, has a climate eminently cold. It freezes there in
the middle of the month of May, near to Santa Fee, and a little
further north (under the parellel of the Morea,) the Rio del Norte
is covered, sometimes several years in succession, with ice so thick
that horses and carriages pass on it.’ Essay on New Spain, vol.
i. p. 103.
4 The environs of El Paso are a delicious country, which re-
semble the most beautiful parts of Andalusia. The fields are cul-
tivated in corn and wheat. The vineyards produce excellent
wines. The gardens contain in abundance all the fruit trees of
Europe.’ (Vol. iii. p. 306.)
££ Humboldt,” continues Benton, 44 is right, and recent travellers
now confirm what he wrote in 1804. It was at the head of the
valley of the Del Norte, some three degrees north of Santa Fee,
that Col. Fremont suffered his great disaster—had to struggle
through snows above the heads of men and horses, and found it a
relief to tread the river, solid with ice, for a road. At Santa Fee,
the 20th of February, it was winter; eight days afterwards, on the
Rio Abajo, half way to El Paso, and having descended 2600 feet,
and still 1200 feet above the level of El Paso, it was spring, the
farmers plowing and seeding, the early fruit trees in bloom, and
the air so mild that he camped out at nights without tents, though
in a settled and hospitable country.”]
Having noticed some of the peculiarities of different climates,
and having shown that they modify more or less the constitutions
of all who come within the sphere of their continued action, the
question naturally arises : can man, with his constitution thus
moulded by his native climate, remove to a foreign country with-
out risk of injury to his health, or of suffering from disease ? We
answer, without hesitation, in the negative.
The history of European colonization and conquest, especially
in the East and West Indies, and in Northern and Central Africa,
exhibits a frightful loss of life, owing to the changes of climate
and the difficulty of acclimation. Even in our own country, we
have seen with what a great sacrifice of life have been accom-
plished, first the settlement of our Atlantic, and afterwards that of
our Southern and Western States.
Yearly, the natives of the Northern States, who in the
pursuit of commerce, or of pleasure, make a sojourn in the Caro-
linas or in Louisiana, pay the penalty of disease, and too fre-
quently of life itself.
A knowledge of these and similar facts, must make us slow to
credit, at least to the extent generally entertained, the opinion that
man possesses the power of adapting himself to all changes of cli-
mate. A recent writer, M. Boudin, in an article entitled “ Etudes
de Pathologie Comparative,”* formally protests against such an
opinion, “a belief of which, he thinks, not resting upon any experi-
mental basis, could only have originated from what has been ob-
served of a fraction of humanity represented by what we call the
Caucasian race.” “ From the earliest times to our own day, we see
the European fail in all his attempts at acquiring a permanent hold
upon the land of Egypt; where, also, the Negro and the Mameluke
are shown to be incapable of procreating beyond the third gene-
ration. In Corsica, the Italian termination of family names proves,
of itself, the inability of the French to establish their stock upon
that island. Where, in the north of Africa, do we find the de-
scendants of the Romans and the Vandals? Why, in America,
♦Ann. d’ Hyg. and de Med. Leg., 1849.
continues Boudin, after passing the 36th degree of latitude, do we
meet with slavery everywhere, unless where the elevation of the land
mitigates the deleterious influence of an excessively increased
temperature ? The height above the ocean which gives pro-
tection to the life of a European, in hot climates, becomes fatal
to the negro. Out of 53 black soldiers posted at Ninera Elia,
in the island of Ceylon, at 6200 feet above the level of the sea,
15 died before the end of the year. In the earliest times, despot-
ism made use of exile into countries alien to their nature, for the
destruction of different nations. With this view, after the de-
struction of Jerusalem, were a great number of Jews sent to Sar-
dinia, on the occasion of whose exile Tacitus makes the following
reflection: ‘ Et si ob gravitatem coeli interissent, vile dammum.’
After the w’ar of the Morea, Mehemet Ali, wishing to get clear of
the undisciplined Arnouts, sent them to the shores of the Red Sea,
where in a few years, 1800 men were reduced to 400,1 by the mere
influence of the climate.” A forgetfulness or an ignorance of the
incompatibility of certain races with particular regions of the earth,
has caused an immense loss of life and the failure of the most
costly expeditions. “ Thus, in 1817, a negro regiment, placed in
garrison at Gibraltar, was almost entirely destroyed by pulmonary
consumption. In 1841, the expedition to the Niger failed, perhaps
owing to the bad selection of the crews of the vessels. In three
weeks after having entered the Niger, 130 out of 145 white men
were attacked with fever, and 40 sank under it. Out of 158
negro sailors, on the other hand, born in America, in the West
Indies, or on the coast of Africa, 11 only were assailed by fever—
but 9 of the cases were fatal. Thiers, in his history of “ the Con-
sulate and the Empire,” shows the dreadful loss of life among the
French troops employed in the invasion of St. Domingo. “But
7000 or 8000 men remained out of an army of 32000; 15000
were carried off in two months. At the same time, in which
Toussaint l’Ouverture, the sinister prophet who had foretold and
longed for these disasters, died of cold in France, a prisoner at the
fort of Joux, our soldiers sank under the piercing rays of a de-
stroying sun.” It would be easy to multiply examples to the same
effect; all going to show the heavy tax paid by those who adven-
ture into remote lands, and into climates differing from that of
their nativity. Not only are immense numbers carried off by dis-
ease, but the survivors are reduced below their former standard of
bodily strength and mental vigor, and thus are made an easy prey
to disease; and in some places it has been doubted whether the
engrafted stock could last many generations. Twining asserts
(Johnson op. cit.) that, in the delta of the Ganges, such is the in-
fluence of its climate, the unmixed European race becomes ex-
tinct at the third generation.
Notwithstanding, however, all these instances, we are forced to
admit that the human constitution undoubtedly possesses the power
of accommodating itself to new, and oftentimes to the most oppo-
site, climatic influences; and this not merely in the case of a few
individuals, but ’of entire communities, and even of great na-
tions. A notable example is afforded in the case of the Jews
who are scattered over the habitable globe—all of them re-
taining features which mark their common origin. But still, if
we compare a Dutch with a Spanish Jew, and these again with
a Jew of Malabar, we observe a striking difference in their
appearance; and also And them exhibiting the shades of com-
plexion, the color of the skin, and the general external develop-
ment, indicative of the climatic influences to which they are re-
spectively subjected, and which approximate them to the natives of
these different countries. We see clearly, that though the race is un-
mistakeably continued, it has undergone changes, only to be at-
tributed to the influence of a new and foreign climate.
It now remains for us to enquire into the changes by which the
process of acclimation is accomplished. First we shall speak of
those effected by a removal from a cold to a hot climate, or in
other words, Southern acclimation.
We have seen that, in a cold climate, man’s circulation and
respiration must be active; that his nutrition must be good, in
order to supply the materials for the development of heat sufficient
to protect him from the injurious influence of the cold atmo-
sphere by which he is surrounded. In this condition, he is car-
ried to a tropical climate, where the active evolution of heat is
not only unnecessary, but injurious; he arrives with all his organs
actively discharging their respective functions ; developing a quan-
tity of heat far exceeding the demand. Were it not for the abun-
dant perspiration that accompanies this functional excitement, the
new-comer would be exposed to the most imminent danger.
It is owing to this fact that, as experience shows, the acclima-
tion of delicate, weak, or old persons, is more easily accomplished
than in the case of those possessing strong, energetic constitutions,
and with a tendency to plethora.
The stranger, in a hot climate, is subject to the following
changes: His circulation becomes accelerated; he suffers extremely
from excessive heat; is subject to the most distressing restless-
ness, in his being for a time utterly unable to procure sleep ; and he
exhibits a strong tendency to local congestions, particularly to the
intestinal canal, brain, liver and skin. All strangers, however,
are not thus affected ; nor can we give any fixed, invariable des-
cription that will be applicable to all. We see some affected with a
trival indisposition, which soon disappears, and they are well.
Some, after continuing for a few days slightly indisposed, are
attacked by an affection of brain, liver or intestinal canal, by
W’hich they are frequently carried off: others, without any previ-
ous warning, are suddenly seized with a fatal inflammation of
these organs. The greater number, however, at first, seem
to be but slightly affected by the change of climate; but, by
degrees, their bodies are emaciated, their strength declines, languor
and debility are depicted upon their countenances, and they, un-
consciously, becomes victims of chronic diseases of the liver and
intestinal canal.
From what has been before stated, we are prepared to learn that
countries in the same latitude, do not exert the same influence
upon strangers. We find that these cquntries, owing to peculiar
situation, temperature, and many other circumstances, give origin
to different diseases, and thus operate in a different degree upon
new comers.
It would carry me too far from the immediate subject of this
essay, and occupy too much time, to enter fully into this subject;
hence I must content myself by making the general statement, that
countries of the same latitude, however different may be their
endemic diseases, and however different their primary effects, pro-
duce ultimately about the same mortality. Though many exam-
ples might be quoted, the following from Andral (op. cit.) affords
a good illustration of this point. “ Out of one thousand British
troops sent to Jamaica, it was found that four to five hundred of
them perished during the first eight months ; wrhile out of an
equal number sent to Madras during the same period, only sixty to
seventy died. But this disproportion diminished as their sojourn
continued, so that at the end of two years the number of deaths,
in the two stations, was nearly equal.” In the former case, they
were carried off by yellow fever, or some similar disease, which
rarely occurs more than once to the same individual; and as the cli-
mate is mild, they that escape this attack, afterwards enjoy good
health; whereas, in the latter place, near Madras, they are exempt
from yellow fever and other such epidemics, so that few die at first,
but after remaining awhile, exposed to the climate, with its atmo-
spheric extremes, their constitutions become enfeebled and broken
down, and they are carried off in great numbers by dysentery, or
some disease of the stomach or liver.
(To be continued.)