202
CLIMATE
so far as occupation by the white race is concemed.
Many elderly persons and those who are overworked
may find rest from nervous tension in the enervating
climate of the tropics. The drier districts are to be
preferred to the moister, the higher altitudes to the
lowlands, coasts and islands well ventilated by pre-
vailing winds, to regions where the air is stagnant.
Much-needed relief from the heat at sea-level may
be obtained by resort to tropical mountain stations,
and many of these have become well-known health
resorts. Tropical mountain climates resemble the
climate of the temperate zones in their lower tem-
peratures and in certain other ways, but they can
never be the equivalent of a temperate zone climate,
for they lack the seasonal changes. Some tropical
climatic characteristics disappear with altitude, while
others change little. The non-seasonal character of
tropical mountain climates, the so-called “ perpetual
spring,” is not by any means the best fitted for man’s
physical and mental development, however pleasant
it may be for a time. With increase of altitude, there
is a decrease in, or a disappearance of, some of the dis-
eases which prevail near sea-level, such as malaria,
yellow fever, liver abscess, etc. When introduced
from the lowlands, such diseases are not likely to be
severe, or to spread. In their stead, however, may
come an increasing frequency of diseases which are
characteristic of high latitudes, such as rheumatism,
and heart and lung troubles. Tropical hill stations
in India show a smaller mortality among the troops
TEE EY01ENE ÓF TEE ZONES
203
than do lower levels. In India, as elsewhere in the
tropics, hill stations are beneficial in restoring those
who are exhausted by overwork or by the heat of the
lowlands. They are especially advantageous for
delicate women and children. Nevertheless, climates
which are temperate because of altitude in the tropics
cannot replace climates which are “temperate” be-
cause of latitude.
The acclimatisation of the white race in the tropics
is a question of vast importance. Upon it depend
the control, government, and utilisation of the tropics.
It is a very complex problem, and it has been much
discussed. It is complicated by the Controls exercised
by race, diet, occupations, habits of life, and the like.
To discuss it fully is impossible in this place. The
gist of the matter is this: White residents from cooler
latitudes on coming into the tropics must adjust
themselves physiologically to the new climatic condi-
tions. During this adjustment there is more or less
strain on various organs of the body. The strain
may be too severe; then the individual suffers. The
adjustment is usually much retarded and hindered by
a persistence in habits of food, drink, and general
mode of life which, however well suited to the home
climate, do not fit tropical conditions. During the
adjustment, especially if complicated by irrational
habits, the body is naturally sensitive to the new dis-
eases to which it is exposed. Even should no specific
disease be contracted, there are anaemic tendencies and
other degenerative changes. Experience teaches
204
CLIMATE
that white men cannot with impunity do hard man-
ual labour under a tropical sun, hut that they may
enjoy fairly good health as overseers, or at indoor
work, if they take reasonable precautions. Accli-
matisation in the full sense of having white men and
women living for successive generations in the tropics,
and reproducing their kind without physical, mental,
and moral degeneration,—*. ecolonisation in the
true sense,—is impossihle. Tropical disease and
death-rates, as has been abundantly shown, can he
much reduced by proper attention to sanitary laws,
so that these rates may he not much, if any, higher
than those in the extra-tropics. And with increas-
ing medical knowledge of the nature and prevention
of tropical diseases, as well as by means of modern
sanitary methods, a white resident in the tropics will
constantly become better ahle to withstand disease.
As Manson has put it, acclimatisation is less “an
unconscious adaptation of the physiology of the
individual” than “an intelligent adaptation of his
habits.” For greater comfort, for better health, and
for greater success, properly selected hill stations
will, however, always be essential to northemers who
have to live in the tropics, especially to white women
and children.
It has heen well said that the white soldier in the
tropics is “ always in campaign; if not against the
enemy, at least against the climate.” This sentence
may he made to fit the case of the white civilian in
the tropics by making it read: the white race in the
THE HYGIENE OF THE ZONES
205
tropics is always in campaign against its enemy, the
climate.
Temperate Zones: General. Far from being
temperate as regards the general climatic conditions
over much of the land area of the so-called temper-
ate zones, these beits rightly deserve their name only
in the sense that in their physiological effects they are
intermediate between the equatorial and the polar
zones. In the temperate zones the organs of the
body act more equally than in the warmer or the
cooler latitudes. In the central part of the temper-
ate zones, especially over the continents, are found
the four seasons. The winter cold is met by means
of warm clothing, heated houses, and other means of
protection. Unless too severe, or too prolonged, when
deaths by freezing may occur, the cold of a Continen-
tal winter in the north temperate zone acts as a health-
ful stimulant upon body and mind. In the tropics,
the body is unused to adjusting itself to tempera-
ture changes, because such changes are there slight,
and is readily affected by them. But the frequent,
sudden, and severe changes of many parts of the tem-
perate zone are usually borne without serious dis-
comfort or injury, if the body is in good health, and
is accustomed to adjusting itself readily to these
changes. The habit of keeping houses very warm
during the winter, and of having the air indoors very
dry, weakens the body’s power to resist the great cold
outdoors, especially if the air be damp, and causes
affections of throat, lungs, and nose. The summers,
206
CLIMATE
although hot in the lower latitudes of these zones,
and marked by spells of warm weather even to their
polar limits, are not characterised by such steady,
uniformly moist heat as is typical of the tropics.
When the heat is extreme, and the relative hu-
midity is high, night and day, sunstroke and kin-
dred affections are occasionally noted in places,
but the invigorating cool of autumn and winter are
never far off, and may always be trusted to bring
relief.
Winter and Summer Diseases. It is natural that
marked seasonal and sudden weather changes, such
as those which characterise much of the temperate
zones, especially in the northem hemisphere, should
be reflected in the character, distribution, and fre-
quency of the diseases which are found in these zones.
Diseases of the respiratory system, bronchial and
rheumatic affections, diseases that result from colds
and chills, pneumonia, bronchitis, influenza, diphthe-
ria, whooping cough, are all common in climates with
sudden marked temperature changes, especially if
those changes are accompanied by cold, damp winds.
These diseases are also most frequent in the winter
months, when the weather changes are more common
and more severe, and when, in consequence, the vital-
ity of the body is lowered and its power of resistance
against the attack of disease germs is weakened. A
greater prevalence of diseases of the respiratory or-
gans, catarrhs, and rheumatic affections in cool, moist
weather, with sudden changes, has been shown by
THE HYOIENE OF THE ZONES 207
Weber, and several investigators have found a higher
mortality after a greater variability of temperature.
Many contagious or infectious diseases, such as diph-
theria, influenza, measles, and scarlet fever, for ex-
ample, are also more common in the colder season, not
because the lower temperatures are the direct control-
ling factor, but largely because the colder weather
drives people indoors; houses and buildings generally
are less well ventilated; more clothing is worn, less
attention is paid to personal cleanliness, and there
is increased opportunity for contagion, especially
among the poorer classes. Obviously, these are in-
direct effects of meteorological conditions. Other
factors, also, must be taken into consideration. Thus
one reason why the natives of the farther north, where
the winters are very severe, suffer less from some of
the diseases which are common in warmer latitudes
is not because of the lower temperatures, but because
they are less exposed to contagion owing to less com-
munication with the outside world.
In the warmer months, fevers and diseases of the
digestive system, diarrhoea, malaria, typhoid fever,
are prevalent. Thus there are usually two maxima
of mortality: one in the colder season, when the vari-
ability of temperature is greatest, chiefly due to re-
spiratory diseases, and another in the warmer months,
largely due to infant mortality from diarrhoeal
disorders.
Tvberculosis. “ A nationally self-inflicted, un-
necessary, and preventable pestilence ”; world-wide
208
CLIMATE
in extent; found in every variety of climate, and at
all altitudes; causing from 10 to 15 per cent. of all
deaths; the scourge of the temperate zone, tuber-
culosis is, on the whole, less frequent in higher
latitudes, on mountains, and in arid or semi-arid dis-
tricts. Climate, however, is not the controlling fac-
tor in the latter cases, but sparseness of population
and infrequency of communication with the outside
world. The density of population; the social and
economie conditions; the occupations and habits of
the people,—these are important Controls. Over-
crowding amid unsanitary surroundings, absence of
sunlight, impure air, are predisposing causes.
Weather, or other conditions which decrease the vi-
tality, increase the susceptibility to tuberculosis.
Sudden temperature changes, especially with high
relative humidity at low temperatures, cause chills
and lower vitality.
Consumption, it is clear, can be successfully treated
where pure air, abundant sunshine, good food, and
outdoor exercise are to be had. The first of these
desiderata, pure air, and plenty of it, is the most im-
portant of all. It is usually found on desert, ocean,
mountain, and in forest. Hence such climates are
generally advantageous m the treatment of tuber-
culosis of various kinds. Yet climate is no longer
believed to play as important a róle in the matter
as was formerly assigned to it. Good hygiene has
to a large extent replaced climate. A health resort
THE HYGIENE OF THE ZONES 209
where a patiënt can find comfortable quarters, con-
genial company, plenty of diversion, and where
favourable climatic conditions, such as abundant sun-
shine, absence of disagreeable winds, dust, and sudden
weather changes, encourage outdoor life, is to be
recommended. The climate does not cure; it is an
important help in the treatment of the disease. Some
patients, especially elderly people and those suffer-
ing from nervous, cardiac, or bronchial affections,
fare better at lower altitudes; but higher altitudes,
with the stimulating effects, deep respiration, and ac-
tive use of the lungs which they induce, often offer
many climatic conditions favourable to outdoor life
and hence of great benefit in the treatment of the
disease. The dry, pure air and abundant sunshine
of many of the well-known mountain health resorts
are very favourable climatic helps. Moreover, the
smaller temperature ranges of mountain and marine
climates are also helpful. In many, if not in
most cases, any change of climate is beneficial, but
especially so if such a change is accompanied by the
favourable conditions just enumerated. Ocean air,
although damp, is beneficial to many patients because
of its purity, its salinity, and its small temperature
ranges. Hence an ocean voyage, with its relief from
unsanitary or harmful occupations, may be an ex-
cellent restorative. Results obtained in the treat-
ment of tuberculosis by climatic change vary through
a wide range. The reasons for such discrepancy are
210
CLIMATE
to be sought in the difference in the stage of the dis-
ease treated, and in the habits, food, and mode of life
of the patients.
Pneumonia. Pneumonia is found almost every-
where, in the tropics probably quite as conunonly as
in colder latitudes, and at high altitudes as well as at
sea-level. A greater frequency of pneumonia gen-
erally follows cold, damp weather, with marked
changes of temperature, which lower the vitality and
are conducive to chills. Hence the disease is most
prevalent in the colder months. Among the predis-
posing causes, physical weakness following other dis-
eases is potent, as are mal-nutrition and similar
debilitating agencies. Severe cold spells are likely
to he followed by an increase of pneumonia, espe-
cially among elderly persons and children. Negroes
who have gone to cold climates are very subject to
the disease.
Diphtheria. Although geographically widely dis-
tributed, diphtheria is chiefly a temperate zone dis-
ease, occurring sporadically or epidemically, however,
in tropics and polar latitudes. Like other infectious
diseases of the temperate zone, diphtheria is most
frequent in the colder months, because the conditions
of life are then most favourable to contagion, and
because vitality is then most lowered by the prevail-
ing weather conditions. Diphtheria is more common
at low altitudes than high.
Influenza. The well-known disease, “grippe,”
caused by a specific organism discovered in 1892, is
THE HYGIENE OF THE ZONEB
211
occasionally very serious, and is apt to be closely
followed by epidemics of pneumonia and other dis-
eases of the respiratory organs. Although very
carefully studied, there is no certain evidence of any
influence of weather, climate, or soil upon the disease.
The last great epidemie of influenza, in 1890 and
thereabout, is believed by Assmann to have been
associated with dry spells and with the carriage of
dust. The worst outbreaks have been in the colder
season, when indoor life, less fresh air, and overcrowd-
ing would naturally help to spread the contagion.
The fact that those who are suffering from influenza
are often not kept indoors explains a general spread
of the disease.
Bronchitis. Bronchitis is most common in the
higher latitudes, and in the cold months, when the
temperature is low and when sudden and rapid varia-
tions of temperature are frequent. Dust, blown from
the dry surface of streets and the like, helps to irritate
the throat and nasal passages. Belief from bron-
chitis may be found where the climate is warm and
uniform; the air soft and balmy; where there are no
irritating winds driving the dust to and fro, and
where sunshine is abundant.
Rheumatism. Rheumatic affections are, as a whole,
more common in colder than warmer, and in damper
than drier climates, but may be classed under the
temperate zone. Exposure to cold and wet, bring-
ing on chills, and sudden temperature changes, es-
pecially in damp climates, while not the cause of
212
CLIMATE
rheumatism lowers the vitality in such a way that the
specific cause may assert itself. In many cases a
change of altitude makes no difference whatever; it
may, in fact, aggravate the trouble.
Measles and Scarlet Fever. Both measles and
scarlet fever are independent of weather and climate,
except in so far as the colder, more inclement, months
involve an unhealthier mode of life, with less atten-
tion to sanitary measures. A maximum is usually
found in the colder months, when infection is most
likely. Measles occurs in all climates, but usually
most commonly and most severely in temperate lati-
tudes. Scarlet fever is essentially a disease of the
temperate zone. Isolation from sources of infection
is more important than any climatic control in these
diseases, which show very various relations to season,
altitude, and race.
Typhoid Fever. Typhoid fever is found in al-
most all parts of the world. Although common in
the tropics, being one of the most generally fatal
diseases there, especially among recent European
arrivals, it is not, according to Manson, properly
classified as a tropical disease. It is very prevalent in
the temperate zone, having a maximum frequency in
late summer and autumn, and is certainly largely
preventable by good sanitation and pure food and
water. The germs of typhoid fever are killed in a
few hours under direct sunshine, and their growth is
slow even in diffused daylight. The well-known
studies of Pettenkofer, at Munich, showed an inverse
TEE BYÖIENE ÓF TEE ZONES
213
relation between the ground-water level and the pre-
valence of typhoid, but this appears not to he a
universal relation. The view formerly held regard-
ing a connection between temperature and humidity
and typhoid epidemics has now generally been
abandoned.
Whooping Cough. Whooping cough is more
prevalent in temperate and cooler climates, where the
temperature changes are marked and where the
respiratory organs are most affected, and is rare and
less severe in warmer latitudes. But the absence of
whooping cough is doubtless often to he explained
on the ground that it has not been imported, rather
than on any direct climatic basis. Although com-
moner and more severe in the cooler months, epi-
demics may occur at all times, without relation to
altitude. Croup, also, prevails chiefly in damp, cool
weather, with sudden changes.
Cholera Infantum. Among the summer diseases
of the temperate zone, cholera infantum occupies a
very prominent place. It increases with rising, is at
a maximum with maximum, and decreases with fall-
ing, temperatures. The greater and more continu-
ous the heat, the more general is the disease. Cool
spells check it immediately. It is more common in
the overcrowded and overheated quarters of the city
than in the country, and may be greatly checked by
the use of pure milk and fresh food.
Hay Fever. The specific cause of hay fever has
been much debated, but is generally regarded as
