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means fermentation, and that it is derived from the Greek Çuμe, leaven-hence the term zymotic disease, which has been applied to certain diseases upon the supposition that the processes by which these diseases are developed bear close analogy to the process of fermentation, as observed in the fermentation of saccharine fluids or vinous fermentation. I wish to lay special stress upon the fact that it was the character of the vinous fermentation alone that suggested the application of the term zymotic to diseases, as, when it was first introduced into medicine, the vinous was the only fermentation studied, even if others were known; the term zymotic disease is now used as synonymous with infective disease. The use of the term zymotic is one which, I believe, has done more to retard the progress of the study of the diseases to which it is applied than most of the other numerous pathological misnomers with which we are troubled, and the use of the term has, I think, tended to impress upon the minds of even scientific observers the idea that observations upon fermentation of various kinds will determine the nature of the processes which take place in some of the infective diseases. I shall now discuss, as briefly as possible, the amount of light which the pathology of the infective diseases may derive from the study of fermentation. Probably the best definition of the term "fermentation" is that given by Professor Miller-namely, "Various transformations which organic compounds experience under the influence of a small quantity of organised matter, which is itself in a state of active alteration." "This active substance, which is termed a ferment, neither imparts anything to nor receives anything from the substance which is undergoing fermentation." In the vinous fermentation we find that the introduction of the yeast plant into a saccharine fluid determines the fermentation of such a fluid, and the conversion of the sugar contained therein into alcohol and carbonic acid. The yeast plant will not increase nor multiply in such a fluid, if it contain sugar only. The sugar will ferment but the plant will die. For the plant to continue its existence, a proper soil for it to grow upon must be provided, and this soil must contain nitrogenous elements to nourish the tissues of the yeast plant; but such growth and such pabulum is unnecessary for the production of fermentation alone. If the yeast plant be washed with distilled water, its power of fermentation is diminished-indeed, it may be temporarily suspended, although the life of the plant is not destroyed. It thus appears that the fermentation is caused by a Elements of Chemistry. Part III., 1857. P. 102.

a product of the growth of the plant-not by the plant itself. That an active principle, capable of itself producing powerful effects on other bodies, can be developed during the growth of such tiny organisms as the yeast plant, is just what might be expected when viewed by the light of the analogous results which take place during the growth of higher vegetable organisms. Thus the various poisons existing in vegetables are the products of the growth of the plants from which they are obtained. These agents, when separated from the plants, are not in any sense living, but are capable of producing as direful results upon human beings, the lower animals, or in some cases even upon plants, as any which have been attributed to disease germs. Some of these active principles may even be produced artificially.

I do not propose to discuss the various forms of fermentation, which seem now to be almost innumerable, but wish to call your attention to a process, strictly homologous to, if not identical with, fermentation, which has a most important bearing upon the question of the infective processes of disease.

There are certain little organisms whose name, "bacteria," is now in the mouth of everyone. They are as generally talked of as if those who discuss them were intimately acquainted with their appearance and nature. The name, in consequence of sensational lectures, has come to be commonly employed in the same sense as

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disease germ; so bacteria and germs are now looked upon as almost equivalent to "plague and pestilence." Now bacteria in themselves appear for the most part to be harmless little creatures; they or their germs swarm in millions in the air we breathe, the fluids we drink, and the food we eat. They can be collected from our mouths at any time, and when washed clean by distilled water have been injected into the blood without producing any evil result. It is quite clear that if bacteria were possessed of the terrible powers attributed to them they would soon have the world to themselves, having eaten up or decomposed all other organised beings. In spite, however, of the apparent harmlessness of these bacteria, it seems now to be almost certain that their existence is necessary, though their presence not essential, to the production of some of the most terrible forms of zymotic or infective diseases with which we have to deal. One disease (anthrax) is said to depend upon them (Pasteur). It is at this point that the study of

a

• Proceedings of Academy of Medicine of Paris. July 3rd, 1877. Medical Record October, 1877. Pp. 428.

fermentation throws important light upon the nature of some forms of zymotic disease; it is because bacteria take part in a certain fermentation that they are important from one point of view. It is now agreed by all investigators that if septic material—that is, decomposing animal matters-be introduced into the blood of an animal, it produces poisonous effects. The result may be immediately fatal, or the effect may be slight and the animal recover, but of the effects of this poisoning I shall have more to say hereafter. A poisonous septic fluid may be prepared by infusing animal tissue (eg., muscle) in water, and when this becomes putrid, boiling it with alcohol, removing the alcohol by filtration and evaporation, and extracting it with water. This fluid contains septic poison, capable of destroying life, yet, whatever the poison be, it has not been destroyed by boiling alcohol. It has been proved by a welldevised and beautiful series of experiments that the poisonous fluid contains neither bacteria nor germs of any kind; the poisonous matter can, however, be filtered out by a porcelain filter. Now, having ascertained that the fluid containing the poison is free from germs, it is necessary to find out the source of the poisonous material. It arose from the putrid infusion of animal tissue, but how did it get there? It may be now considered as proved, by the observations of Dr. Burdon Sanderson and others, that this virulent poison is the product of a fermentation in the infusion of muscle, the fermentation being promoted by the presence of bacteria, just as the vinous fermentation is promoted by the yeast plant; the ultimate result in the former case being the septic poison in the latter, alcohol, or, as we may fairly call it, the alcoholic poison. I must here mention that the bacteria, which first appear in organic infusions or cultivating fluids, do not possess the power of producing a septic poison, but the succeeding generations produced by these bacteria do possess this power. The first generation of bodies do not present the same appearance as those which follow bacteria, having the appearance of little rods, produce as offspring, not rod-like bodies, but spheroidal bodies, called micrococci, which have a tendency to collect into masses (gloa) in which the bodies appear to cohere by means of a gelatinous substance. So much then for the relation of fermentative processes to the production of disease, and it amounts simply to this—that certain fermentations generate poisons, which in their turn may produce diseased conditions.

Reports of the Medical Officer of the Privy Council and Local Government Board. New Series, Nos. VI. and VIII.; and British Medical Journal, 1875, 1877, and 1878.

SPONTANEOUS GENERATION.

The next question to be considered is the relation of what is termed "spontaneous generation" to the production or promotion of disease. Spontaneous generation has been and usually is taken to mean "the production of living things from materials not previously endowed with life; the term is objected to by Dr. Bastian" under the belief that any operation performed either by the action of physical or vital laws, cannot be considered spontaneous. He has proposed to employ the term "archebiosis." While I quite agree with Dr. Bastian, yet I think it better to employ the more familiar term "spontaneous generation." In approaching the consideration of this subject, I know that I am not alone treading on the domains of the special pathologist and physiologist, but also venturing on the more dangerous and sacred ground of the theologist. Now with all deference to those who object to the consideration of the question of "spontaneous generation" on the ground that it has been declared in Holy Writ that "God made heaven and earth, and the sea and all things that are therein" (Acts, xiv. 15), I must say I do not consider the inquiry impious, because the inquiry is not whether the Almighty did or did not create a particular thing, but simply how he created it.

It has been said that those who assert the truth of spontaneous generation, and the belief in the evolution of higher from lower organisms, in obedience to certain natural laws, do by such assertions disparage the creative power of God, but I cannot see that they do so on the contrary, I believe that such views imply rather a more perfect creative power in the Deity. To illustrate this: A well-trained skilful mechanist can make a watch-it may be that some engineer may even devise a machine to make a watchbut it is utterly beyond the compass of a human mind to make a series of laws which, by their working, will make a watch; and similarly I say that that Almighty power which can create a series of laws which, by their own working, will produce living organisms from formerly non-vital material, is the greatest creative power which the finite mind can imagine. I do not come before you, however, as an advocate of spontaneous generation—on the contrary, taking an impartial view of all the evidence yet produced for or against the theory, I am distinctly of opinion that at present the supporters of this theory have got the worst of the discussion, and

* Modes of Origin of the Lowest Organisms.

1871.

must produce further evidence and new facts to prove their case. I cannot possibly enter upon the discussion of the experiments which have been made with the view of proving the statements put forward on either side, but I shall refer to the more essential observations. The belief in spontaneous generation is very old. Aristotle (584, B.C.) believed in the spontaneous production of plants and animals. Harvey (1578) combated the views of the supporters of spontaneous generation, and of irregular physiological speculations generally, adopting as his maxim, "omne vivum ab ovo." Such a light seemed necessary at that time, for we find the following gravely written by Gerardes in his "Herbal," in 1597:"There are found in the north parts of Scotland, and the islands adjacent, called Orchades, certain trees, whereon do grow certain shells of a white colour, tending to russet, wherein are contained little living creatures; which shells in time of maturity do open, and out of them grow those little living things which, falling into the water, do become fowls, which we call barnacles." And, further, "but what our eyes have seen and our hands have touched we shall declare:-There is a small island in Lancashire called the Pile of Foulders, wherein are found the broken pieces of old and bruised ships, some whereof have been cast thither by shipwreck, and also the trunks and bodies, with the branches of old and rotten trees cast up there likewise, whereon is found a certain spume or froth that in time breedeth into certain shells, in shape like those of a mussel, but sharper pointed, and of a whitish colour; wherein is contained a thing in form like a lace of silk finely woven as it were together, of a whitish colour, one end whereof is fastened into the inside of the shell, even as the fish of oysters and mussels are; the other end is made fast unto the belly of a rude mass or lump, which in time cometh to the shape and form of a bird; when it is perfectly formed the shell gapeth open, and the first thing that appeareth is the foresaid lace or string; next come the legs of the bird hanging out, and as it groweth greater it openeth the shell by degrees, till at length it is all come forth, and hangeth only by the bill. In short space it cometh to full maturity, and falleth into the sea where it gathereth feathers, and groweth to a fowl bigger than a mallard and lesser than a goose." Here we have spontaneous generation and Darwinian evolution all demonstrated in a most concise and off-hand manner. It was upon such statements

as the above that the proof of spontaneous generation rested until very recent times, when the exact experiments of physicists

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