The causation of disease : an exposition on the ultimate factors which induce it

Preface

The object of this work is to trace out the ultimate causes of disease — not of particular diseases — but of disease in general.

In writing a work of this kind two courses are open to the author. One is to saturate himself with all the available literature on the subject, and, having done so, to connect into an intelligible whole the facts and opinions thus gleaned, adding, amending, and omitting as may seem fit. The other is for him to think the subject out independently from beginning to end, and to draw upon the resources of literature only just so far as apposite matter may chance to present itself in the ordinary course of his reading, or as his line of thought may from time to time suggest some special reference.

I have adopted the latter course, not, indeed, from any preconceived plan, but rather from the force of circumstances, which led me in the first instance to think out the subjects here treated of for my own personal benefit.

And, on the whole, I am inclined to think that the second of these two methods is the better ; for, although the author is put to the pains of thinking out for himself questions which have already been decided, and, moreover, runs the risk of being charged with plagiarism, his work is far more likely to

VI PREFACE.

bear the stamp of originality, and lie escapes the very considerable danger of being a mere compiler.

While correcting the proof-sheets, I had the advantage or reading Mr. Mitchell's work on "Evolution and Dissolution," and this suggested some of the remarks on this subject contained in Chap. XII. , Part I. My indebtedness to this author was, through oversight, not acknowledged in the text ; but with this exception I have, I believe, in all cases acknowledged the authorities I have made use of.

H. C.

Part I

CHAP. PAGE

I. General Eemarks on Causation i

II. The Causation of Gross Material Effects — The Causation of Atomic

and Molecular Effects 6

III. The Causation of the Vital Changes of Protoplasm— Definition of

Structure as applied to Living Matter — Proper Method of Studying the Causation of Disease 1 1

IV. The Environment — The Environment of Unicellular Organisms —

The Internal-Cell-Environment of Multicellular Organisms — The Primary Mai-Environment — The Secondary Mai-Environment— Remarks on the Nomenclature of Disease . . .17

V. The External-Body-Environment — An Analysis of it — Its Divisions into Organic, Inorganic, Mental, and Physical — The Distinction between a Diverse and Complex External-Environment — Summary of this and the preceding Chapters .... 29

VI. The Causation of Structure — The Two Great Causes of Structure :

Heredity and Environment 36

VII. The Causation of Structure {continued) — Heredity — Sexual and Asexual Reproduction — Reproduction by Simple Division — Parthenogenesis — Graft Hybridism — Partial Reproduction — General Principles .40

VIII. The Causation of Structure {continued) — Heredity — The Grand

Rhythm of Life — Minor Vital Rhythms 49

IX. Causation of Structure (continued) — Heredity at Corresponding Ages — Heredity at Corresponding Seasons — Sexual Heredity — Some Comparisons between Man and Woman 57 viii CONTENTS.

CHAP

PAGE

X. Heredity (continued)— The Principle of Structural Mean— Prepotency— Physiological and Pathological Blendings . . 74

XI. Heredity (continued) — The Fixity of Structural Characters in Inverse Proportion to their Age, Ancestral or Individual — All Diseases' of Recent Ancestral Date — The Vis Medicatrix Naturce — The Tendency of Recently Acquired Characters to Disappear under Ancestral Forms of Environment ... 84

XII. Heredity (continued) — Reversion—Its Two Chief Causes — Peculiarity in the Evolutionary Process and Partial Dissolution of a Mature Tissue . . . 104

XIII. Heredity (continued)— A Consideration of the Different Modes by which Organic Potentialities may become Actualities — Some further Bearings of the Principle of Reversion upon Pathology — Summary 115

XIV. Heredity (continued) — Influence of the Male Element upon the Female Organism — Inheritance of Acquired Structural Characters 123

XV. The Causation of Structure {continued) — The Influence of Ante-

partem Environment upon Structure 127

XVI. The Influence of Environment upon Structure — The Influence of •

the Ante-partem Environment (continued) — Differences in E the Prime Cause of Natural Variations 138

XVII. The Influence of Environment upon Structure (continued) — The Influence of the Post-partem Environment, considered from the Pathological Point of View 147

XVIII. The Morbid Inter-action of Structure and Environment— All Disease Processes probably attended by Structural Change, and therefore Natural Variations — Structural Deficiency . 156

XIX. The Symbolical Method of Expressing the Relative Share taken

by Structure and Environment in Causation .... 163

XX. Some Further Applications of the Symbolical Method . . .168

XXI. Recapitulation j^.

CONTENTS. IX

PAET II.

CHAP. PAGE

I. The Evolution of Species — Natural Selection — Sexual Selection

— The Action of the Environment independently of Selection 185

II. Natural Selection — " Instinct and Eeason '" — Instinct a Perfect

— Reason an Imperfect Guide 191

III. Natural Selection (continued)— The Influence of " Reason" upon

Natural Selection 201

IV. Natural Selection (continued) — The Purely Accidental Causes of

Death — Mai-Environments — The Necessarily-Fatal Environment— The Not-Necessarily-Fatal Environment — The Necessary Mai-Environment 205

V. Natural Selection (continued) — Deficiency of Food only an Indirect Cause of Death in Civilized Communities . . . 210

VI. Natural Selection (continued) — The Frequency of Natural Variations in Man — The Influence of Natural Selection on the Mental Side of Man 214

VII. Natural Selection (continued) — Its Influence on the Corporeal Side of Man — Disease, a Necessary Evil — Active Operation of Natural Selection in consequence of Instability of the Environment—Perfect Adaptation Impossible — Illustrations . . 222

VIII. Natural Selection (continued) — Adaptation to Micro-organisms — The Instability of these latter interferes with the Process of Adaptation 232

IX. Natural Selection (continued) — The Necessarily-Fatal Environment 240

X. Natural Selection (continued) — The Environment afforded by the

Country 249*

XI. Natural Selection (continued)— The Comparative Activity of the

Process in Civilized and Primitive Man and in the Lower Animals — The Relation between the Activity of the Process and the Health of the Community 253

XII. Natural Selection (continued) — Curtailment of the Number of

Births in a Community hinders Evolution and favours Dissolution 261 c CONTENTS.

CHAP. PAGE

XIII. Activity of Natural Selection at the Different Periods of Life Compared— Its Influence on the Hereditary Transmission of Disease at these Periods — Natural Selection Inoperative after the Procreative Period— Non-Transmission of Evolutionary Gains after this Period— Average Limit of the Procreative Period of Life in the Two Sexes 264

XIV. Sexual Selection 273

XV. Action of E upon Structure independently of Selection . -277

XVI. Criticism of Dr. Mott's Views — Concluding Eemarks on Evolution 280

Part III

I. The Distinction between a " Natural " and an " Artificial Environment" 284

II. What constitutes Normality in Structure and Environment — Definition of Health— Test of Healthy Inter-action — The Actually and Potentially Normal — The Inevitably Abnormal — Justification of the Term Kesistance as Applied to Disease . 290

III. To what extent Structural Abnormality occurs during the Actual

Time of Disease 303

IV. The Advantage of Changed Conditions of Life upon the Vital

Organism 3x5

V. Heredity 3^

VI. Disease not an Entity — All Disease comes through E — The

Variability of Disease— A Perfect Classification Impossible . 331

VII. The Parasitic Origin of Malignant Growths 342

THE

CAUSATION OF DISEASE,

P A E T I.

Chapter I. General Remarks On Causation

Since the chief object of this essay is to inquire into the ultimate causes of disease, it is necessary at the outset to attach a definite meaning to the word Cause.

There is ,no subject in the whole range of philosophy which has excited greater interest than that of Causation ; but this is not the place to enter fully into it. I propose, therefore, to say only just so much upon it as is needful for a philosophic treatment of the subject in hand, and my remarks on this head will furnish the keynote to the method adopted throughout this work.

Suppose the question were asked : What is the cause of gravitation ? The reply would be : Gravitation is an ultimate and undecomposable property of matter — that is to say, one which cannot be simplified or referred to any wider principle behind or beyond it. It has, therefore, no cause, for cause implies an antecedent, and gravitation has, as far as we know, no antecedent.

Again, let the questions be asked : What is the cause of 0 uniting, or, in simpler language, why does 0 unite, with H in the proportion to form water ? Why does H unite with CI to form hydrochloric acid? Why, in short, does each element behave in a way peculiar to itself in respect of its power to combine with other elements ? The answer again is : These properties of elements are ultimate and unanalysable properties, just as gravitation is ultimate and unanalysable. Such ultimate properties — or, as we may term them, primitive causes — have, as far as we know, no beginning, and therefore we cannot say that they themselves are caused, for cause implies an antecedent, and therefore a beginning, and that which has no beginning can have no cause.

Starting, however, with these ultimate or primitive causes, we observe that an infinite variety of effects may be produced by a modification of the material conditions; indeed, every effect with which we are acquainted may be thus produced,' whether mental or physical. What do I mean by material conditions ? Under this term I include : kind of matter (0, CI, H), quantity of matter, motion of matter (atomic, molecular, or massive) ; finally, disposition of matter, or, as I should be inclined to denominate it, " structure"

Now, given certain material conditions, the same result will always follow. This is the Law of Causation. Man has discovered — that is to say — from long observation of Nature, that her operations are fixed and unchangeable. We do not find a certain effect follow upon certain material conditions to-day, and another effect follow upon the same conditions to-morrow. We observe, on the contrary, certain regular sequences, and these, when put into words, are called laws. Thus, none of Nature's laws are fickle and irregular, but fixed and unchangeable.

I shall then define the cause of any particular effect as the sum of those material conditions from which that effect has necessarily followed*

How far it is psychologically permissible to refer all phenomena to "material conditions," as above defined, matters

* I desire to make two remarks on this definition. First, I do not mean by li any particular result" any like result, but one particular result which has happened. The same result may follow from different causes— e.g., heat —therefore in the definition I prefer to speak of one special instance. Secondly, I wish it to be understood that I use the term nun in the strict algebraical sense, it includes certain conditions and excludes all conditions which do not take part in, or would interfere with, the result.

little to us, so long- as the conclusions deducible from this assumption shall aid us in the practical concerns of life. The physician can have nothing to say to any portion of philosophy which cannot be reconciled with utilitarianism ; but, although I would gladly escape the psychological aspect of the question, it is advisable to state — very briefly — wherein the a,bove definition of cause is psychologically deficient.

First, the definition assumes a material world, but it is utterly impossible to prove the existence of such material world, since we have no knowledge of anything but our own mental states. Of anything outside of or apart from mind, we can know nothing. Inasmuch, however, as the assumption of a material world and of material conditions, as above defined, by no means interferes with the conclusions based thereon, so far as they affect the practical conduct of daily life, we are at perfect liberty to assume the existence of a material world. I, therefore, unhesitatingly speak of material conditions, although it would be psychologically more correct to speak of phenomena — of that which seems to be (= the phenomenal) as distinguished from that which is (= the noumenal).

A second point which, from the psychological point of view, deserves notice, is that no mention is made of " Force " among the material conditions. Our conception of force is the mental ingredient out of which our conceptions of matter, space, time, and motion are built.* It will only be necessary to refer to the first two of these. Matter is ultimately known to us through its manifestations of force, through the resistance, namely, which it opposes to our muscular energies. This resistance is twofold ; for, first, matter resists our efforts to push it out of position, and is capable of pushing us out of position — whence arises the idea of repulsion ; and, secondly, it resists our efforts to rend its several parts asunder (= cohesion), and hence arises the idea of attractive force. We conceive of force, therefore, as something which attracts and repels. A little thought will show that matter can only be known to us through its manifestation of force (= resistance), for '-abstract this, and nothing but empty extension remains." But, on the other hand, we cannot think of force

* Vide Herbert Spencer's " First Principles," § 50.

B 2

(= resistance) apart from matter ; and, being thus unable to mentally separate the two, we are justified in including, under kind of matter and quantity of matter (= mass), both the matter and the force which is inseparable from it. As regards the different " kinds " of matter, this force is peculiar for each kind, since each separate kind has specific powers of attraction and repulsion.

It follows that there is no need to make specific allusion to " Force " among the material conditions above defined. It will further be observed that no mention is made of " Space," but this idea is embodied under "Disposition of Matter," which signifies the relative positions which the particles of matter occupy in space.

Out of the material conditions above enumerated all the effects within our experience can be obtained, be they physical or mental. I mean by this, that all phenomena (the word is convenient) could be referred to these material conditions, did we possess the power of analysing the conditions out of which they arise ; that, in investigating the origin of any phenomenon, our search should be directed towards this end ; and that, when we have discovered the material conditions out of which that phenomenon has arisen, we possess the most perfect knowledge of its causation which it is possible for us to obtain.

I say the causation of mental phenomena, alike with that of physical phenomena, can be expressed in terms of " material conditions." Whatever psychological incongruity there may appear in this, we shall find nevertheless — once more to appeal to utilitarianism — that the conclusions obtainable from this assumption are such as help us practically. What is the connection between mind and matter matters little to us, for it is now generally recognized that in every mental sequence there is a corresponding physical sequence, and that there is a close correlation between mental capacities and tendencies on the one hand, and cerebral structure on the other ; so that, in dealing with causes of mental phenomena we shall still have to do with material conditions.

According to the Law of Causation the same conditions are always followed by the same result, and, while speaking of the causation of mental phenomena, it is well to remark that there is only one exception to this law which has been advanced with any cogency — viz., the Power of the Will. It is argued by the supporters of the Freedom of the WW, that this faculty may act differently under exactly the same circumstances — that is to say, the motives to action remaining the same (both in respect of quality and quantity), the Will, unfettered by any rigid principle of cause and effect, is free, by a power peculiarly its own, to determine action in any given direction. It is probable, however, that the will forms no exception to the Law of Causation.

Since, then, every effect can be referred to material conditions, it follows that in studying the causes of disease our search must be directed into the material conditions out of which disease arises.

Chapter II

The Causation of Gross Material Effects— The Causation of Atomic and Molecular Effects.

Let ns now briefly apply the conclusions arrived at in the last chapter — first, to gross material effects; and secondly, to the more minute atomic and molecular effects. Under this latter head are included the chemical changes of protoplasm, the sum of which constitutes life. Having thus acquired a scientific insight into the causation of atomic and molecular phenomena, and consequently of the vital changes of protoplasm, we shall (I believe) be in a position to define the cause of disease in intelligible terms, disease being an abnormal mode of life.

First, as regards gross material effects : let us, in theory, construct a planetary system containing a given number of worlds, each having a definite mass and velocity, and all bearing definite relations to one another. In such a case, we are ourselves the choosers of the material conditions, and we can, from two well-known laws, calculate the resulting complex series of movements with the utmost accuracy, the two being : the law of universal gravitation and the first law of motion. These laws are simply verbal expressions of sequences which are the outcome of the ultimate properties of matter already spoken of. What then is the cause, in this hypothetical case, of the complex series of movements ? It is the sum of the material conditions. Let any one of them be altered — e.g., the mass of any one world— and the entire series of movements will be changed. It is very important to note that all the material conditions which take part in the production of a given effect constitute the cause, and not any one of them.

To make this point clear, let us conceive a nicely constructed balance placed in vacuo ; let all friction be removed, and then let us suspend from each arm a ton weight. There will be perfect equilibrium. If now, a grain weight be added to one of these ton weights, the latter, we can assert positively, will descend with a certain degree of momentum. Now, it would be vulgarly said that the particular grain is the cause of the descent, for, the two ton weights exactly balancing one another, the grain will fall to the earth as it would do if left unsupported in vacuo ; but, as a matter of fact, every other grain in the descending ton weight takes an equal share in pulling it to the earth j and, if the slightest particle be removed from the other ton, the result, as expressed in terms of momentum, will be modified, and the same will happen if the slightest friction be added. We cannot, therefore, refer the cause of descent to any one particular grain of matter ; the sum of the material conditions of our conception constitutes the cause.

Secondly, as regards atomic and molecular effects. In the above examples we are dealing with gross material conditions, with obvious and palpable matter — matter, that is, which is capable of being recognized as such by the senses. But beneath the world of our every-day life there is a world of the infinitesimal. Our senses take cognizance of quantities ranging within very narrow limits, and although the intellect can reason with vast and infinitesimal quantities, our knowledge of quantity above and below a certain narrow range is merely symbolical — that is to say, we can only represent it by symbols — it is beyond our realization. Let us remember that this difficulty of conception in respect of quantity is not confined to the immense. We are apt to forget this, unmindful of the fact that a second is split up into billions of parts by a vibration of the violet ray of the spectrum, and that the atomic particles of a protoplasmic cell may be as small in comparison with the cell as is this latter in comparison with our earth. Knowledge (I use the term advisedly, assuming that we can measure such quantities accurately) of this kind is only symbolical; but because our senses are thus limited in range, we must not turn in disdain from the subject, but rather try diligently — let the success be never so slight — to form some faint conception of these infinitesimal quantities.

Now, according to the theory of Dalton, matter is not continuous, but consists of particles called atoms. This theory has been steadily gaining in .strength since Dalton's time, and is now placed upon a firm basis. There are about seventy different kiuds of atoms. These are united, by what is called chemical force, into molecules, and these latter are, in the case of solids and liquids, held together by the physical force of cohesion. I mentioned kind of matter as one of the material conditions which are at the root of all phenomena. The term refers to the different varieties of atoms. Each kind of atom, we must suppose, possesses certain fundamental, undecomposable properties, and these properties relate to the power which each atom possesses of attracting to itself other atoms, so as to form different kinds of molecules. It may be that all these atoms are decomposable,* all possibly consisting of different groupings of still smaller particles of only one kind of matter ; and it may also be that the chemical and cohesive forces are but varieties of one force — the universal force of gravitation. Such possibilities must have occurred, I imagine, to most men who have thought carefully over this subject, but whether it be so or not — whether the atoms and these two forces be analysable or not — none of them have yet been analysed, none therefore have, logically, any cause. We must accept each as a fundamental, undecomposable fact. This remark also applies, of course, to gravity, which itself may possibly not be an ultimate property ; but the possibility of any presumed ultimate property being decomposable does not prohibit the assumption of its undecomposability until the reverse is proved. It does not, that is, negative on the ground of illogical treatment, the general results arrived at.

We are now in a position to apply the definition of cause to

* Loekyer has put forward the hypothesis that all the elements are really compound— i.e., different kinds of aggregation of one kind of matter. According to this hypothesis, the matter of which the universe is composed, was at one time equally distributed through space, and uniform in kind, although made up of atoms. These then aggregated into two's, three's, or more, and then again into " elements." This hypothesis rests upon evidence gained by observing different elements under excessively high temperatures (as of the sun) by means of the spectroscope ; the spectroscopic characters suggesting decomposition of the elements into simpler bodies. — Phil. Trans., 1874, V- 49 ct eeq.

chemical action. All chemical action is governed by " material conditions/' and the material conditions of which chemical action is the outcome are — (i) The presence of certain kinds of atoms. (2) The arrangements of these atoms — i.e., their relation one to another. (3) The kind of motion by which these atoms, and -the molecules formed of them, are agitated — namely, heat, light, electricity and such like modes of .motion. In seeking for the " cause " of any particular chemical change, we can do no more than discover the material conditions as just set forth. These, as Bain would say, " are the final terms of the explanation." Viewing the matter thus, we see how little is the difference between astronomy and chemistry. We must not, in our blindness, despise the tiny atom, for, in the eye of the natural philosopher, it is as important as any great world rolling through space, and, indeed, the analogies between the two are very great : both world and atom are indestructible and eternal ; each is governed by fixed and unchangeable law ; and, if an atom is small by the side of the world, so is a world small by the side of the universe. A group of worlds, arranged in a planetary system, is akin to a group of atoms forming a molecular system ; the atom, like the world, is the seat of movements both about its own axis and about a point outside itself; finally, both the planetary and the molecular systems have a definite structure, which may be defined as the mutual positions which the constituent parts, whether worlds or atoms, bear to one another.

That the structure, or mutual position of the several atoms in the molecule determines very largely the nature of that molecule, is well shown in the case of the so-called isomeric bodies — that is to say, unlike bodies whose molecules contain the same number of the same kind of atoms. The primary, secondary, and tertiary alcohols afford a familiar example. These are isomeric, but each differs from the other in its chemical properties, and chemists have actually attempted to determine the molecular structure in each case. Thus :

I I

I I

H H

OH

Primary Secondary Tertiary alcohol,

alcohol. alcohol.

Not only have the constituent elements of a planetary and of a molecular system a definite relation to one another, but each of these smaller systems forms part of a larger system, for each planetary system stands in definite relations to other celestial groups, and each molecular system is definitely related to the surrounding molecules.

Chapter III

The Causation of the Vital Changes of Protoplasm — Definition of Structure as applied to Living Matter — Proper Method of Studying the Causation of Disease.

In the latter portion of the last chapter we dealt with the causation of atomic and molecular phenomena in general. Let us now treat of the causation of those atomic and molecular changes occurring within living protoplasm.

A protoplasmic cell consists of myriads of molecules, and in contemplating the structure of such a cell we must include both the mutual relations of the atomic constituents of the molecules, and the relations which these latter bear amoug themselves. Protoplasm is often spoken of as homogeneous. If the molecules were regularly arranged throughout the entire cell protoplasm, the latter would be in a sense homogeneous, though still possessing a structure, but we have no right to assume auy such regular arrangement of molecules in protoplasm; indeed, we are a priori compelled to conclude otherwise. The fact that the cells of different tissues have different functions proves that their structure is different. This follows from the law of causation, but it is not possible for the most accomplished histologist to refer to its proper order every individual cell that is at haphazard given him for examination, though he may recognize them when grouped together into tissues.

When it is said that protoplasm is homogeneous, it is meant that it is a homogeneous jelly-like matter, which, however, may be moulded into various forms — that is to say, though the general configuration of the cell may differ, it is assumed that the substance of which it is built up is homogeneous. For instance, nerve ganglion cells, blood corpuscles, and kidney epithelial cells — notably some of them — -are quite

THE CAUSATION OF DISEASE.

unlike in gross configuration, though they are made up, it is supposed, of a homogeneous substance. This is a false supposition, and is disproved by three facts: — (i) Dr. Klein has

Fie. i.

Ganglion Cell from anterior Horn or Cornu of Grey Matter in the Spinal Cord of a Calf, b, Processes abruptly broken off. a, The axis cylinder process. Magnified about 800 diameters. (Max Schultze.)

long proved that protoplasm contains a complex network. (2) Many cells, especially nerve-cells, show a very distinct structure {see fig. 1). (3) Finally, as I have already said, differences in function are a distinct proof of differences in structure. Think, for an instant, of an impregnated ovum and of the vast potentialities locked up within it. There is little difference between the apparent structure of a human ovum and that of many belonging to the lower animals ; but the fact that each develops into an entirely different being, shows what a vast difference there must be in the minute structure of each. One might be pardoned for lingering long on a subject like this. Who, possessed of any imagination, can think of the microscopic ovum-cell without feeling wonder? It appears to consist of nothing but a very slightly differentiated protoplasm ; but this is simply because our senses are limited in scope, and are unable to take account of what we may, somewhat paradoxically, term the vast world of the infinitesimal. The potentialities of the ovum are the outcome of certain material conditions. In this tiny cell are aggregated billions of atoms and molecules. These are arranged in peculiar ways, and it is upon the nature of the atoms, the arrangement of the atoms into molecules, and of these latter among themselves, that the subsequent developmental changes depend — just as the complex movements of the heavenly bodies depend upon the nature (mass, &c.) of the individual heavenly bodies, the arrangement of these into planetary systems, and the relations of the planetary systems one to another. Thus we may speak of the heavens as possessing an infinitely complex structure, and thus also all analogy leads us to assume that an ovum-cell, or indeed any other mass of living protoplasm, is endowed with a structure so subtle and intricate as to be out of the reach of man's limited faculties.