What is malaria? : and why is it most intense in hot climates? an enquiry into the nature and cause of the so-called marsh poison with remarks on the principles to be observed for the preservation of health in tropical climates and malarious districts

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Preface

The opinions expressed in the following pages, upon the origin of malarious fevers, — (a subject of worldwide interest and importance,) differ so materially from those of many men distinguished for scientific attainments and professional eminence, that I should feel much diffidence in publishing them, were they not theresult of much reflection, observation, and enquiry r together with considerable experience in my own person of the diseases referred to.

Some remarks of Dr. B. W. Richardson, relating to the connection between meteorology and disease, appear so applicable to the subject treated of in this work, that I cannot do better than repeat his words.

“ We observe great outbreaks of disease, and we look for their primary cause : says one, it is ‘ epidemic influence/ says another, it is ‘ germs,’ ‘organic germs/ says a third, it is ‘malarious air/ and so on, each having a theory and adding to it some learned reason, or so-called practical inference

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PREFACE.

or moral ; and all omitting to enquire what may be the action, in regard to causation, of common changes of atmosphere combined or uncombined with natural physiological changes in the living organism.”

Brought face to face with endemic malarious disease, in all its forms, I found it impossible, under any of the usually accepted theories, to account satisfactorily for many of the phenomena attending its production ; I set myself, therefore, to find out something definite as to its nature and origin.

After much careful enquiry, I arrived at the conclusion that malaria, as a specific poison, does not exist.

Further, I became convinced, that the diseases usually attributed to “malarious influence” are caused by chill, or in other words, by the sudden abstraction of heat ; and the more closely the circumstances connected with the development of these disorders were enquired into, the more firmly did this conviction become established.

I found, moreover, that the greater prevalence of “malaria” in hot climates, and the graver type of the diseases produced there, could in this way be readily accounted for; together with several phenomena, which are irreconcilable with the usually received theories on the subject.

I am of opinion that many diseases, besides ma-

PREFACE.

Vll larious fevers, arise from the cause which I have named ; especially dysentery, hepatitis, and others witli which these fevers are very closely connected. But to avoid confusion, it may be well to mention, that the term malarious disease is, in the present work, intended to apply only to the intermittent and remittent fevers, of which “ malaria” is so generally considered to be the cause.

In conclusion, I take this opportunity to offer my thanks to those friends, who have kindly ' assisted me with information and otherwise; and especially to Dr. Thomas Inman, who long ago taught me to take nothing for granted, but to observe and to think, to which lesson is mainly due this enquiry into the nature and cause of u Malaria.’*

London. December, 1870.

*

Chapter I. General Observations

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What is Malaria? — General ideas on the subject — Hygienic arrangements based on supposed origin of malaria in vegetable decomposition — Correctness of this theory often doubted, but no other has yet supplanted it— Malarious fevers chief cause of sickness over a large portion of the globe — Till nature and origin of malaria fully understood, little can be done to check its destructive effects — Prevalence of malarious disease in India — Mortality directly resulting from malarious fevers bears but a small proportion to that indirectly caused by them — Malarious diseases and their ill effects well known from a very early period, though their origin is still disputed—" Malarious fevers those with which the ancient physicians were best acquainted— Hippocrates does not refer to marsh miasma, though aware of the prevalence of disease in marshy places — Probably knew malaria was not a marsh poison —Other ancient writers on the subject — Avicenna alludes to vegetable decomposition — In more modern times Lancisi a great champion of the theory of “ marsh poison.” — Ascribed malaria to decomposition of animal as well as vegetable matters — Pringle’s observations — Opinions of Lind, Annesley, Fergusson, Williams, McKinnon, Morehead, Bennett, Parkes, Martin, Aitken, Salisbury, and Niemeyer . . . . 1

Chapter II

GEOGRAPHY ETC. OF MALARIA.

Northern and southern limits of malaria — Focus of malaria in tropics — In Northern Europe, malaria rare except in marshy districts, and on banks of rivers — In the south with a warmer climate, it is found in dry and barren places — In Asia and America the distribution of malaria follows the same laws — In the southern Hemisphere both in New and in Old World similar changes are observed in the distribution of malaria, in proceeding from the south towards the tropics — Intensity of malaria increases with heat of climate — Some countries have been erroneously supposed to be free from malaria — Australia — Ireland — In hot climates, no localify free from malaria — Climatic influence shown, by increased heat being attended with greater prevalence and malignancy of malaria, and by its extension to seasons and situations, which in cooler climates are exempt — Malaria season not always in Autumn, but varies with climate — Where fevers prevail in hot weather, type always severe — In equatorial regions rainy season most malarious and dry season most healthy — In some countries malaria very prevalent in cold weather 12

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Chapter III. Various Theories Considered

Theory ascribing malaria to decomposition of organic matter has had most

supporters in Modern Times Ancient physicians attributed the uidiealtLiness

of marshy places cliieliy to unwholesome water or to damp, f; ggy air Avicenna appears first to have ascribed noxious qualities to decomposing vegetable matter such as flax — But ascribed same properties to bitumen — Laucisi quotes Avicenna as his chief authority — Controversy on subject of flax steeping — Observation that malaria may exist without a marsh caused a modification of this theory, ascribing it to organic matters in the soil —On same basis late writers advocate theory which ascribes malaria to drinking water- — Prevalence of malaria in marshy places led to the idea that malaria was a marsh poison — Swampy districts generally abounding with luxuriant vegetation, this from association became considered the cause of malaria — To this day “ rank vegetation” exterminated by sanitarians with little result — Some marshes almost entirely free from malaria — Bogs of Ireland — Singapore — Amazon valley — If malaria caused by vegetable decomposition, why are these exempt ? — In hot and swampy equatorial countries, the healthiest period is when banks of rivers and lagoons are most exposed, and the most unhealthy season, when they are covered with water — When the Thames was comparatively pure agues were rife in London, but when the river was most foul they were almost unknown- — Mangrove swamps — Humboldt’s experiments — Livingstone’s experience — If malaria be caused by any product of vegetable decomposition those most exnosed to such products should be most frequently affected by them — Is this the case P — Tanners not more liable to ague than other people — When refuse bark laid down in streets, ague not produced — Market gardeners — Farmyards and stableyards — Steeping of Sunn or Indian hemp — Indigo refuse — Preparation of flax in north of Ireland — Preparation of hemp and flax supposed to produce malaria, but malaria due to locality — In some cases those living near a swamp escape malarious disease — Jail at Goojrat — Author's experiment 21

Chapter IV. The Connection Between The Forest And Malaria

Decomposition of vegetable matter supposed to be the cause of malaria in forests — Connection between malaria and the forest not more constant than between malaria and the marsh — Clearing of forests has sometimes been attended with disappearance or diminution of malaria — But malaria does not always disappear with the woods, and exists where trees do not — Some forests highly malarious, others free from malaria, though vegetable decay occurs in each — Malarious forests generally wet and healthy forests generally dry — Malaria prevails in the swampy forest, under the same conditions as in the marsh — As malaria is found where there is no marsh, so it prevails in some forests which are not swampy — In marshy ground forests retain dampness of soil — In damp situations only, does any benefit arise from clearing forest or jungle — Trees in themselves, harmless in temperate and highly beneficial in hot climates —

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Belts of trees said to arrest malaria and planting suggested as a means of rendering swamps healthy — Trees in the Soonderbuns, Terai, or forests of

Orinoco do not produce any such effect — Trees will not render a marsh healthy, nor a well-drained country unhenltliy — Even swampy forests not all equally malarious — Why this difference ? — Trees have been supposed to attract malaria — Morehead’s remarks — Safest place at night iu a malarious country, is in a tree or under it — Natives of India and other countries spend their nights under trees — So also do animals in all countries — Largo spreading trees objects of veneration and the planting of trees in halting places an act of piety — In a swampy district, largest trees generally on driest ground — Trees radiate heat slowly, and diminish variations of temperature — The warmest place at night under a tree 32:

Chapter V. Malaria Without Vegetation Or Stagnant Water

Malaria sometimes very intense in damp places, though vegetation or surface water is absent — Coasts, of Holland — Flats of Brabant — Wilmington — In hot climates malarious fevers prevail in arid places and during great drought — Hennen’s and Morehead’s observations— Fergusson’s cases in the Peninsula — Severe malarious fever in Abyssinia, amongst troops encamped in dry bed of torrent — Mortality amongst horses at same time — Humboldt’s observations on malaria in Llanos — The Sahara — Mean Meer in the Punjab — Desert of Rajpootana — Jacobabad in Scinde — Malaria amid barren rocks and hills — Gibraltar — Ionian islands — China — Aden — In hot climates rocks considered to cause fevers — Central India— South America — Dr. Heyne on ferruginous granite rocks — Granite of Gong Kong — Limestone of Scinde — Fevers in such places not from marsh poison 33

Chapter VI. Some Supposed Sources Of Malaria

Idea of marsh water causing malarious disease very ancient— Malaria not confined to the neighbourhood of mnrshes, nor to drinkers of marsh water — In India, soldiers, officers, and civilians often drink from same source, yet soldiers suffer most from malarious disease — In many places water containing vegetable matters, and not filtered, is drunk without producing malarious fevers — Dr. Eatwell’s observations in China — Dr. Falconer, on travellers in the Terai — Sir J. Pringle, on the water in Holland— Dr. Parkes, on the water of Sierra Leone — In Northern India, water supply chiefly from wells, often in barren places, yet no exemption from malaria — Epidemics arise and subside, the people still drinking water of the same quality and from the same source — Recently excavated soil said to produce malaria — Hong Kong — Analysis of soil — Malaria existed previous to excavations — Excavations in healthy districts do not cause n^ilaria — Damp or marshy ground malarious with or without excavation — Superficial soil contains more organic matter than subsoil — Cultivation, which involves disturbance of the soil, supposed to destroy malaria — Diminution of malaria really due to drying of soil, and consequent climatic changes— Sir J. R. Martin’s remarks— Malaria very prevalent iu some highly cultivated districts — Mere fact of being cultivated or uncultivated does not render a district malarious or otherwise—But drying of a damp soil does generally diminish disease . . .49 xn

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Chapter VII. Various Theories Further Considered

The origin of malaria has been sought in certain geological formations — In hot climates, no formation free from malarious disease, and in cold climates, it is not confined to any particular rock or soil — Stiff retentive soils or impervious subsoils sometimes favour development of malaria, but it exists where they do not — Dr. Falconer’s opinion — No proof of any connection between electricity and malaria — Gases evolved in marshy places do not cause ague — Dr. Aitken’s remark — Sulphuretted Hydrogen not malaria — Some have supposed malarious disease to be caused by living organisms — -Dr. Salisbury’s reported discovery — Objections to his theory — Dr. Salisbury’s later observations — Further remarks on his theory — Whatever the origin of infectious diseases, malarious fevers, which are not infectious, cannot arise from the same or a similar cause — Dr. Salisbury’s views not confirmed .............. 56

Chapter VIII. The So-called Paludal Cachexia, Is It Caused By A Specific Poison ?

Malaria sometimes said to produce a “paludal cachexia,” accompanied, or not, by malarious fever — A generally enfeebled state of health not uncommon in damp marshy localities, especially in hot climates — -Effects of combined heat and moisture on white races — Also of repeated attacks of malarious fever - — Occasionally aggravated by tendency to scurvy — Cachexia, sometimes met with in natives of hot climates, due to repeated attacks of fever — Often aggravated by want of proper food — Malaria may prevail extensively without causing cachexia, except as a consequence of attacks of fever — Case in point — Action of quinine, in malarious fevers and paludal cachexia, considered a proof of their origin in a specific poison — No foundation for this — Quinine a most beneficial remedy in many affections unconnected with malaria — Not a certain cure for malarious fever — Other remedies for the same disease not considered to have any specific action — Quinine not a certain protection against malaria 63-

Chapter IX. What Is Malaria?

The conditions under which malarious disease prevails, very numerous and varied-The same cause must exist in every case-Decaying organic matter, in any appreciable quantity, not always present — Nor when it is so, does it produce malarious fever — No known geological or physical condition of soil or site common to all malarious localities — -Nor any poisonous gas — Nor any peculiarity in the electric condition of the atmosphere — Nor any species of orgauic germ — Thermal and other meteorological conditions afford only opening for further investigation — Sudden variation of temperature to be traced in all histories of epidemic malarious disease — Also, in all descriptions of sites and circumstances favorable to development of malaria — Iso-

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lated cases of malarious fever may be thus accounted for — Relapses of this disease caused by chill- — Twining’s observations — Author’s views — Effects of cold — Effects of heat — Circumstances attending development of malaria point to its identity with chill — Observations of Sir J. R. Martin — Difference between damp and dry cold — M. Brachet’s experiments — Effects of cold bathing, in hot climates — Night air in hot countries often humid and raw — Dr. Mount’s observations — Remarks of Drs. Arnott and Lind . . .67

Chapter X. Influence Of The Seasons Upon Malaria

Prevalence of malarious disease in autumn observed from earliest times — GeneraUy ascribed by modern writers to presence of vegetable decay — - Most striking peculiarity of autumnal season great variation of temperature — Malaria not everywhere most prevalent in autumn, but invariably so at the time of transition from hot to cold season — More so in proportion to suddenness of change — Sir J. McGrigor’s observations — Fever of last autumn in upper India, and its causes— In hot climates any irregularity of seasons produces malaria — Epidemic of 1809 in south of India — Many highly malarious places free from marsh, but remarkable for extremes of temperature — Kamptee — Jacobabad — Marshy places remarkable for freedom from malaria, also remarkable for equability of climate — Ireland — Singapore — Amazon valley 74-

Chapter XI. Characteristics Of Malarious Situations

Two classes of malarious localities — Nightly chill the one condition common to both — In hot or in cold climates, dank night air most prominent characteristic of marsh — This disappears by day — So does malaria — Same thing occurs in other unhealthy situations-Damp localities generally malarious-But not in proportion to the degree of humidity — Damp not malaria — Moisture exaggerates effect of cold — In variable climates malaria often diminishes in rainy season, the temperature becoming more equable — Aqueous vapour and its influence upon climate — Professor Tyndall’s observations — Effects of damp very important in connection with irrigation — Excessive irrigation known to cause deadly malaria — Instance in India — Author’s observations —

Evil effect least apparent in a hot and equable climate — Rice cultivation produces malarious disease in the north of India, but considered harmless and even beneficial in the south — Dr. McPherson’s remarks — I’alaveram — Major- General Cotton’s experience — Dr. Saunders on the fever in lower Bengal — Night exposure in a moist climate, with insufficient protection from chill, liable at any season to produce fever 84

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CHAPTER XII. CHARACTERISTICS OP MALARIOUS SITUATIONS (Continued)

Malaria, its latency by day and energy by night incompatible with its being an organic poison— Exists in swatnps, deserts, and in mountainous regions — Exhalations from marshes consist of aqueous vapour only — Are innoxious during the day — At night, chill and malaria come together — Night air not malarious when dry and warm — Sleeping in open air in hot climates — Intensity of malaria in low situations and feebleness at slight elevations — Wells’ observations — At night, the coldest strata of atmosphere nearest the ground — In hot climates, malarious disease occurs at great altitudes —

The hotter the climate, the greater altitude necessary for safety — Instances of malaria on mountains — Line of malarious influence imaginary — Malarious season varies with altitude and climate — Safety from malaria at great elevations limited to those who are well sheltered and well clothed — Sickness in newly occupied situations often depends upon undue exposure to climatic influences 92

Chapter XIII. Further Characteristics Of Malarious Situations

CONSIDERED.

Water said to absorb malaria — this statement examined — Ships lying off a malarious coast comparatively safe — Explanation — Malarious fevers occur at sea — Instances of this — Influence of winds upon malaria — Winds beneficial when of equable temperature and force — S B. tradewind — Cold winds dangerous in hot climates — N E. Monsoon — Pringle’s remarks on cold night winds — Livingstone’s case — Remarks of Drs.Dick and Vans Best on Stanley, Hong Kong — Cold winds dangerous in mountain gorges — Instances in India — - Dr. A. Smith, on night winds at Pay ta 102

Chapter XIV. Some, Hitherto, Incomprehensible Peculiarities Of

MALARIA.

Malarious fevers on hills and table lands — -In hottest and driest season —

Dr. Heyne’s observations-Fever diminishes on setting in of rains-Dr. Pearse, on Anamallay hills — Dr. McPherson’s remarks — Cause of malaria in some cases temporary — These hills subject to much the same influences as plains — Higher parts of lofty ranges free from “Hill Fever” — Though it may prevail on their lower spurs — Dr. McPherson, on hills near Vizianagram — Prominent characteristic of “feverish” hills — During rainy seasons both temperature and fevers are mild — Night the dangerous time — Natives, who sleep in open air with little clothing very liable to fever — Report of Committee, on sickness at Seringapatam — Emanations from barren rocks supposed to cause fever — Humboldt, on fevers of Orinoco — Explanation — Angostura — Southern India— Hong Kong — Protective influence of fire and smoke recognised in all malarious regions — And from earliest ages — Instances in different countries— Explanation — Malaria less prevalent in towns than in country — Instances and explanation

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Chapter XV

l'age

INFLUENCE OF HEAT IN CONNECTION WITH MALARIA.

Effects produced by continued exposure to a very bigb temperature-H nmboldt’s observations — Remarks of Sir J. R. Martin, and Dr. Morehead — Malarious fevers always most prevalent after great heat-Pringle’s and Fergusson’s observations — Effects of insufficient protection from calorific influences — Pringle’s remarks — Author’s experience — McKinnon’s observation — Cause of unhealthineSs of casemated barracks and forts in India — Effects of exposure to sun — Remarks of Drs. Dick and Murchison — Chill a cause of malarious fevers during great heat and drought — Explanation — Type of malarious fevers aggravated in hot season — Ferguson’s remarks — Fevers more severe after unusually protracted heat, and most malignant in hottest climates — Some forms of fever caused by heat — Dr. B. W. Richardson’s remarks— This class of diseases not considered malarious — Yet most intimately connected with remittent and intermittent fevers — Disorders considered to be result of climatic influences, scarcely distinguishable from others, supposed to be caused by a specific poison — Dr. McKinnon’s remark— Connection between ardent and malarious fevers explained 124

Chapter XVI. Effects Of Exposure To Climatic Vicissitudes

Those most exposed to sudden changes of temperature suffer most trom malarious fevers — Pringle’s observations — Private soldiers suffer more than officers and latter more than civilians — Each class attacked by same diseases— Many attempts to explain this difference but none of them satisfactory— Alcohol is not malaria — Drunkenness often leads to exposure to climatic influences — When this is avoided drunkards scarcely more liable to fever than sober men — Cases in point — Exposure on night duty great cause of sickness amongst soldiers — Observations of Messrs. Snell, Hensman, and Morgan, and Drs. Davy and Murchison — Also of Sir J. Pringle and Mr. Hennen — Mr. Gore, on fever at Sierra Leone — Dr. Livingstone’s experience —Cases of malarious fever from exposure on board ship — Effects of exposure to rain in tropics — Mr. Hare’s observations — Lind’s and Humboldt’s remarks — Native servants in India often suffer from fevers during cold and wet weather, when their white employers escape — In some cases those exposed to climatic vicissitudes attacked by fever, while others not so exposed escape — Instances 136

Chapter XVII

BOTH PRIMARY AND RECURRENT ATTACKS OF MALARIOUS FEVER RESULT FROM SUDDEN CHANGE FROM HEAT TO COLD.

Paroxysmal fever often makes its appearance upon a sudden change from a hot to a colder climate- — Especially if effects of change be heightened by exposure to wet oracold wind — This effect produced even when thechangeistoamost healthy locality — Persons in India attacked with fever for first time on arrival

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at Hill Sanitaria— Samo occurs in Mexico— Same thing happens in Europe to persons arriving from hot climates — Instances So-called relapses of malarious fever arise from chill — Dr. McLean’s remarks Dr. Waring s observations Instances of recurrent attacks of intermittent, after long intervals, in consequence of exposure to cold — Observations of Surgeon Major Small and Assistant Surgeon Power on recurrent attacks of intermittent in H.M. I3tb Regiment — Liability to recurrence explained . 152

Chapter XVIII

BENEFICIAL EFFECT OF CHANGE OF CLIMATE IF PROPER PRECAUTIONS BE OBSERVED.

Occasional change to a cooler climate necessary to maintain the health of white men in the tropics — Observations of Sir A. Tulloch, Sir J. R. Martin,

M. Thevenot and Dr. Morehead — Advantage of temporary removal from presence of great heat always admitted, even when malaria was considered to be a specific poison — Precautions necessary in ca3e of sudden removal to a cooler climate — Such removal most powerful remedy for malarious fevers-Very slight change of temperature often sufficient- Beneficial effect of change of climate explained — Situations in which recovery is certain, in hot season, may, in cold season, produce an opposite effect — Dr. Morehead’s observations— Benefit not produced by removal from presence of any poison, nor from any action of mere cold — In some cases change to a warm climate more beneficial than to a very cold one, though malarious disease may prevail in the former and not in the latter — Case in point 159

Chapter XIX

MALARIA IN CONNECTION WITH ACCLIMATISATION AND THE ALLEGED IMMUNITY OF CERTAIN RACES FROM ITS EFFECTS.

New arrivals in hot climates sometimes suffer more from disease than natives or old residents — The reason explained — Opinions of M. Boudin and Sir J. R. Martin — Under equal circumstances of exposure, tendency to malarious disease increases with length of residence in hot climates — Each attack of fever increases the liability to a recurrence — Owing to a change in constitution, after a certain period heat is borne with less distress, but susceptibility to cold increases — New arrivals more subject to ardent fevers, and old residents to intermittent and remittent — Instances — Dark races affected by unusual heat — Neither in black nor in white men does the constitution ever become malaria proof — Each race suffers least in the climate for which it is most fitted — Precautions taken by certain tribes exempt them in some degree from malarious disease — Negro race said to be proof against malaria— Fergusson’s remarks — Immunity of the Negro comparative only, and limited to hot and equable climates — Observations of Drs. Merrill and Revburne— Malarious disease in the lower animals 166

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Chapter XX. Diseases Related To Malarious Fevers

Close connection between malarious fevers and dysentery, hepatitis, pneumonia and other diseases has been hitherto mysterious — Observations of Pringle, McGrigor, Jackson, Cleghorne, Annesley, Williams, Parkes, Haspel, McLean, and Morehead, on the connection between dysentery and fever — Also of McLean, Bird, Martin, Morehead, and Haspel, on hepatitis and its causes — Each of these diseases occurs in connection with malarious fevers at the same time, in the same place, and in the same person — Rheumatism and thoracic affections often associated with malarious fevers — Latter very frequent in cold season — Observations of Davis, Cleghome, Merrill, and Morehead — The diseases most commonly associated with malarious fevers are such as arise from climatic causes ..... 178

Conclusion

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WHAT IS MALARIA?

AND

WHY IS IT MOST INTENSE IN HOT CLIMATES?

Chapter I. General Observations

What is Malaria? — General ideas on the subject — Hygienic arrangements based on supposed origin of malaria in vegetable decomposition — Correctness of this theory often doubted, but no other has yet supplanted it — Malarious fevers chief cause of sickness over a large portion of the globe — Till nature and origin of malaria fully understood, little can be done to check its destructive effects — Prevalence of malarious disease in India — Mortality directly resulting from malarious fevers bears but a small proportion to that indirectly caused by them — Malarious diseases and their ill effects well known from a very early period, though their origin is still disputed—* Malarious fevers those with which the ancient physicians were best acquainted— Hippocrates does not refer to marsh miasma, though aware of the prevalence of disease in marshy places — Probably knew malaria was not a marsh poison — Other ancient writers on the subject — Avicenna alludes to vegetable decomposition — In more modern times Lancisi a great champion of the theory of “marsh poison.” — Ascribed malai-ia to decomposition of animal as well as vegetable matters — Pringle’s observations — Opinions of Lind, Annesley, Pergusson, Williams, McKinnon, Morehead, Bennett, Parkes, Martin, Aitken, Salisbury, and Niemeyer.

What is Malaria ?

On referring to modern works on Medicine, we find it generally stated, that malaria is a poison given off by organic, especially vegetable matters, in a state of decomposition; and upon this basis are founded the hygienic arrangements of all malarious countries.

Faith in this dogma has many times been shaken, and several authorities have endeavoured to account in other ways for the influence, whatever it be, by which the class of diseases known as malarious fevers is produced ; but none of the theories so proposed have stood their ground.

These diseases, not unknown in temperate climates, increase in frequency and intensity, as we approach the tropics ;

JB where they become the most common, and too often the most deadly, enemies of human life.

Constituting, as malarious fevers do, the chief source of sickness and mortality, over a large portion of the earth, it is evident that to discover the cause of a class of diseases so destructive to the human race, is of the highest importance, not only to medicine, but to political economy ; for until the nature and origin of malaria are fully understood, little can be done to check its destructive effects.

To form a just idea of the importance of malarious diseases it is necessary to consider not only their influence upon the fate of an army, or the result of a war, of which history furnishes many examples ;* but also their powerful effect in checking the spread of the white race, over a large portion of the globe ; and even their influence upon the welfare of this country, intimately connected as it is, with every part of the world. There is scarcely a family in Britain but sends forth some of its members to the regions in which these diseases constantly prevail ; and where few entirely escape their attacks.

The prevalence of malarious fevers in hot climates may be gathered from the fact, that the last Army Medical Report gives the number of cases of paroxysmal fever alone in British India, during the year 1867, which was unusually healthy, as 19,375 in a force of 56,896 men; equal to one man in three. Not only did this occur in a healthy season, but some of the corps which suffered most were cantoned at the cleanest, driest, and healthiest stations in the plains.

. In some instances one corpshas suffered much more severely than another, at the same station, and apparently exposed to the same influences.

At Ilazareebagh, the A. Battery, 16th Brigade Royal Artillery, had ,66 cases of fever amongst 112 men. The 91st Regiment, at the same station, had only 209 cases in an

* In Scinde, every officer and every man, of Sir C. Napier’s army of 1/000 men, was attacked with fever. In some regiments no surgeon was able to visit the hospitals, and the force was reduced to such a state, that had the hill tribes made a raid, they might have plundered the whole country, as scarcely a man could be found fit for duty. Administration of Scinde. p. 72.