It is easier to pull down than to build up; easier to refute than to convince; easier to find fault than to suggest a remedy: and this reflection may occur, and no doubt has occurred, to those, be they few or many, who have perused the preceding chapters of this work. It may now be asked of me explicitly, What is your theory? What is your remedy for the evils complained of? To this I might reply, as the immortal historian of the “Decline and Fall” is said to have done, “If you have read certain chapters of my work with sufficient attention, you may extract from them my meaning and my views;” but as this might imply on my part either a Teutonic love for obscurity in phraseology, or a fear to commit myself to any theory, I shall here sum up in a few words the views I have arrived at after much reflection on the matter, during a long and active life passed in a country supposed to be a hotbed of malaria, the great source indeed of malaria in Western Europe, that land for which nature has done so little and man so much. 1. There floats in the lower strata of the atmosphere in all regions of the earth, but in very various proportions, for reasons already explained, a poison or poisons, generated by the processes which nature adopts for the destruction of past generations, and the reconstruction of those to come; the destruction of the aged, the worn-out, the nearly extinguished; the reconstruction of the organisms springing into life, to occupy the place of those that were! Whether the poison be one or many; whether it be a single species or one of a natural family, does not affect the general conclusions. The diversity of its effects is no proof of diversity in its essential nature or even origin; the living principle is supposed to be of one nature everywhere and for ever; yet see how varied are the results of this principle in moulding the vegetable and animal worlds; how slight are the modifications even in organic elements, which, when called into play, give rise to the most astonishing and unexpected diversity of results. Why should it not happen, then, with the poison, influence, or thing we call malaria, which, modified by a chemical action too subtle for the scientific man to observe, may yet, being so modified, give rise to an intermittent or a remittent, a plague, a cholera, a diphtherite, a scarlatina, a typhus, or a small-pox? Where did so many poisons come from? Whence came the murrains, the vine-plague, the potato-destroying poison, which was not at all new, neither was it confined to the potato? Whence came the pestilences which destroyed the ancient world? which exterminated at once whole species and genera now extinct? Of one thing we may be assured, they did not die a natural death.
2. This poison, whatever it may be, floats in the lower regions of the atmosphere, supported therein by the gaseous products of fermentation, and more especially by the ammonia now proved to exist everywhere in the atmosphere. It is the product, in fact, of the slow combustion perpetually going on in the air, the earth, the waters, wherever, in fact, animal or vegetable organisms are to be decomposed. We call it putrefaction; it is in truth a ferment, and the fermentable matter, that which gives rise to the ferment, is the immediate agent as well as the result (for it is the nature of all ferments to reproduce their process) of this fermentation, accumulated in the lower regions of the atmosphere. Increased to the dangerous point by men’s imprudence or ignorance, quickened by epidemic influences with whose nature we are of course wholly unacquainted, and absorbed by the living tissues, it excites that fermentation, that tendency to putrescence in the living blood to whose results medical men have given so many appellations. At times it is called ague; at times remittent fever; now it is small-pox; and now a fatal diphtherite. To the transit of ferments through the air and to their inhalation by man, I ascribe the diseases usually called zymotic. In ancient primitive times, when physicians were rare,63 and men did not interfere, a poison thus absorbed ran its course from incubation to specific fermentation, with all its results, in a given time, terminating in a crisis which might be calculated and determined; and which might prove fatal or at once remove the disease. A violent perspiration, a severe diarrh?a, a specific and contagious eruption on the surface of the body, proved and effected the elimination of the poison from the system. The ferment had done its work; it had altered the mass of the blood, and the products of the slow combustion (putrescence, rottenness, fermentation) were discharged by the secretions, according to circumstances peculiar to the constitution of the individual: as out of the same materials serpents elaborate poisons of very different powers and qualities, so the ferment, passing through various constitutions, gives rise to various results. It pervades the air and clings to it, nor can it be avoided but by a change of place of residence;64 storms may, and no doubt do, affect it, but they frequently fail in dislodging the poison; intervening wide-spread oceans fail to interrupt its course;65 and as regards the caprice exhibited in its attacks, we have only to reflect on the number of elements, vital, atmospheric, social, and chemical, involved in its full maturescence. Our doubts on all such matters originate probably in the coarse chemical theories and still coarser chemical experiments which prevailed about thirty years ago, and from their influence, from which men’s minds have not as yet escaped. The atmosphere was declared to contain a few wide-spread gaseous elements, and to be unalterable; the air of towns, of theatres, of large heated apartments, crowded with people, was boldly asserted by chemists still alive to be eudiometrically perfect.
§ 1. Discovery of foreign bodies, the remains of animal and vegetable life, and therefore fermentable, in the air floating over canals, ditches, marshes, &c.—Scientific chemists, as well as the professors of the conjectural art, are occasionally behind the knowledge of the careful, observing, unprejudiced practical men of the day.66 Experience taught me, whilst engaged in other inquiries, that the sulphuretted hydrogen gas arising from the waters of the canals of Holland is quite sufficient to spoil cottons printed with nitrate of lead, used for dyeing yellow with the chromate of potass. The waters of these canals hold this gas in solution in a certain sense, but from May to September inclusive, the gas escapes during the night in great abundance.
At this time vapours arising from the waters and floating over the adjoining grounds, were found to contain minute portions of aquatic plants mingled with the spores of fungi in vast abundance, together with fragments of a membranous and gelatinous substance about to be mentioned. To these must be added the remains of infusoria not to be detected in dried specimens.
The injurious effects of water holding such substances, gaseous and solid, in solution, we overcome by boiling and passing the steam through (heated) iron pipes, and re-converting the steam into water. By this process we get rid of the injurious effects of these foreign matters, gaseous and solid, held in a kind of solution by the water, in as far, at least, as they affect the colours used in dyeing.
During these examinations of the waters themselves, it was distinctly observed that the infusoria and testaceous mollusca, microscopic and otherwise, with which such waters abound, were developed in glutinous membranes attached to the aquatic herbs abounding in these waters; in short, these membranes seem to be the matrix for the growth, nourishment, and production (using the term in a limited sense) of these organized beings; they form an essential condition of their existence.
The plants themselves were now washed in distilled water, and the animal products were the semivalve and bivalve shells of which I have preserved many specimens. The semivalve belong to the natural families Buccinum, Lynceus, Helix, and Planorbis; the bivalve to the Cardiac?. The semivalves are the most abundant. By filtering the water which remained after the shells had been removed, innumerable minute particles like dust were discovered; these particles were ascertained by the aid of the microscope to be mainly composed of minute fragments of aquatic plants and of the spores of fungi; to these must, no doubt, be added, although not visible when dried, the remains of zoophytes, and of the glutinous membranes forming the matrix of animal aquatic life.
I now endeavoured to obtain the glutinous membrane or matrix in which these testaceous mollusca were obviously developed, apart and distinct from the animals themselves. To attain this desirable point we filled a glass receiver with water containing the aquatic plants and shells, and the gelatinous membrane already spoken of. The receiver was now inverted upon a plate, and water poured into the plate to the depth of half an inch.
In a few days the receiver became filled with gas, forcing the water downwards into the plate on which the receiver rested; and although after the first day we could not discover any of the gelatinous membranes in the lower part of the receiver, yet that in the plate became like a flaky jelly, attaching itself to blades of grass or leaves. The surface exposed to the atmosphere became dry and brittle, and in this state resembled thin layers of gum; the substance thus desiccated strongly resembled jelly.
The glutinous membrane of which frequent mention has been made above, is of a very viscid nature, and when combined with any animal substance in a state of transition or fermentation, it is poisonous. It is, I believe, generally viewed as the matrix for the development of the ova of these shell fish, and considered as a product or secretion of the parent. Into this question I enter not, leaving it, if it be one, to others.
On exposing for a few days some of the larger testaceous mollusca alive to the atmosphere of the room at a temperature varying from 65° to 70° Fahr., strong proofs were obtained that ammonia was produced in the interior of the shell confined therein by the membrane called operculum, sealing, as it were, the aperture into the shell hermetically. On puncturing this membrane the presence of ammoniacal gas could be distinctly traced by the odour.
I submit to the consideration of professed physiologists the following questions:—1st. What are the effects li............