Where the quant.i.ty of general painful sensation is too great in the system, inordinate voluntary exertions are produced either of our ideas, as in melancholy and madness, or of our muscles, as in convulsion. From these maladies also brute animals are much more exempt than mankind, owing to their greater inapt.i.tude to voluntary exertion, as mentioned in Sect. XVI.
on Instinct.
II. 1. When any moving organ is excited into such violent motions, that a quant.i.ty of pleasurable or painful sensation is produced, it frequently happens (but not always) that new motions of the affected organ are generated in consequence of the pain or pleasure, which are termed inflammation.
These new motions are of a peculiar kind, tending to distend the old, and to produce new fibres, and thence to elongate the straight muscles, which serve locomotion, and to form new vessels at the extremities or sides of the vascular muscles.
2. Thus the pleasurable sensations produce an enlargement of the nipples of nurses, of the papillae of the tongue, of the p.e.n.i.s, and probably produce the growth of the body from its embryon state to its maturity; whilst the new motions in consequence of painful sensation, with the growth of the fibres or vessels, which they occasion, are termed inflammation.
Hence when the straight muscles are inflamed, part of their tendons at each extremity gain new life and sensibility, and thus the muscle is for a time elongated; and inflamed bones become soft, vascular, and sensible. Thus new vessels shoot over the cornea of inflamed eyes, and into scirrhous tumours, when they become inflamed; and hence all inflamed parts grow together by intermixture, and inosculation of the new and old vessels.
The heat is occasioned from the increased secretions either of mucus, or of the fibres, which produce or elongate the vessels. The red colour is owing to the pellucidity of the newly formed vessels, and as the arterial parts of them are probably formed before their correspondent venous parts.
3. These new motions are excited either from the increased quant.i.ty of sensation in consequence of greater fibrous contractions, or from increased sensibility, that is, from the increased quant.i.ty of sensorial power in the moving organ. Hence they are induced by great external stimuli, as by wounds, broken bones; and by acrid or infectious materials; or by common stimuli on those organs, which have been some time quiescent; as the usual light of the day inflames the eyes of those, who have been confined in dungeons; and the warmth of a common fire inflames those, who have been previously exposed to much cold.
But these new motions are never generated by that pain, which arises from defect of stimulus, as from hunger, thirst, cold, or inanition, with all those pains, which are termed nervous. Where these pains exist, the motions of the affected part are lessened; and if inflammation succeeds, it is in some distant parts; as coughs are caused by coldness and moisture being long applied to the feet; or it is in consequence of the renewal of the stimulus, as of heat or food, which excites our organs into stronger action after their temporary quiescence; as kibed heels after walking in snow.
4. But when these new motions of the vascular muscles are exerted with greater violence, and these vessels are either elongated too much or too hastily, a new material is secreted from their extremities, which is of various kinds according to the peculiar animal motions of this new kind of gland, which secretes it; such is the pus laudabile or common matter, the variolous matter, venereal matter, catarrhous matter, and many others.
5. These matters are the product of an animal process; they are secreted or produced from the blood by certain diseased motions of the extremities of the blood-vessels, and are on that account all of them contagious; for if a portion of any of these matters is transmitted into the circulation, or perhaps only inserted into the skin, or beneath the cuticle of an healthy person, its stimulus in a certain time produces the same kind of morbid motions, by which itself was produced; and hence a similar kind is generated. See Sect. x.x.xIX. 6. 1.
6. It is remarkable, that many of these contagious matters are capable of producing a similar disease but once; as the small-pox and measles; and I suppose this is true of all those contagious diseases, which are spontaneously cured by nature in a certain time; for if the body was capable of receiving the disease a second time, the patient must perpetually infect himself by the very matter, which he has himself produced, and is lodged about him; and hence he could never become free from the disease. Something similar to this is seen in the secondary fever of the confluent small-pox; there is a great absorption of variolous matter, a very minute part of which would give the genuine small-pox to another person; but here it only stimulates the system into common fever; like that which common puss, or any other acrid material might occasion.
7. In the pulmonary consumption, where common matter is daily absorbed, an irritative fever only, without new inflammation, is generally produced; which is terminated like other irritative fevers by sweats, or loose stools. Hence it does not appear, that this absorbed matter always acts as a contagious material producing fresh inflammation or new abscesses. Though there is reason to believe, that the first time any common matter is absorbed, it has this effect, but not the second time, like the variolous matter above mentioned.
This accounts for the opinion, that the pulmonary consumption is sometimes infectious, which opinion was held by the ancients, and continues in Italy at present; and I have myself seen three or four instances, where a husband and wife, who have slept together, and have thus much received each other"s breath, who have infected each other, and both died in consequence of the original taint of only one of them. This also accounts for the abscesses in various parts of the body, that are sometimes produced after the inoculated small-pox is terminated; for this second absorption of variolous matter acts like common matter, and produces only irritative fever in those children, whose const.i.tutions have already experienced the absorption of common matter; and inflammation with a tendency to produce new abscesses in those, whose const.i.tutions have not experienced the absorptions of common matter.
It is probable, that more certain proofs might have been found to shew, that common matter is infectious the first time it is absorbed, tending to produce similar abscesses, but not the second time of its absorption, if this subject had been attended to.
8. These contagious diseases are very numerous, as the plague, small-pox, chicken-pox, measles, scarlet-fever, pemphigus, catarrh, chincough, venereal disease, itch, trichoma, tinea. The infectious material does not seem to be dissolved by the air, but only mixed with it perhaps in fine powder, which soon subsides; since many of these contagions can only be received by actual contact; and others of them only at small distances from the infected person; as is evident from many persons having been near patients of the small-pox without acquiring the disease.
The reason, why many of these diseases are received but once, and others repeatedly, is not well understood; it appears to me, that the const.i.tution becomes so accustomed to the stimuli of these infectious materials, by having once experienced them, that though irritative motions, as hectic fevers, may again be produced by them, yet no sensation, and in consequence no general inflammation succeeds; as disagreeable smells or tastes by habit cease to be perceived; they continue indeed to excite irritative ideas on the organs of sense, but these are not succeeded by sensation.
There are many irritative motions, which were at first succeeded by sensation, but which by frequent repet.i.tion cease to excite sensation, as explained in Sect. XX. on Vertigo. And, that this circ.u.mstance exists in respect to infectious matter appears from a known fact; that nurses, who have had the small-pox, are liable to experience small ulcers on their arms by the contact of variolous matter in lifting their patients; and that when patients, who have formerly had the small-pox have been inoculated in the arm, a phlegmon, or inflamed sore, has succeeded, but no subsequent fever.
Which shews, that the contagious matter of the small-pox has not lost its power of stimulating the part it is applied to, but that the general system is not affected in consequence. See Section XII. 7. 6. XIX. 9.
9. From the accounts of the plague, virulent catarrh, and putrid dysentery, it seems uncertain, whether these diseases are experienced more than once; but the venereal disease and itch are doubtless repeatedly infectious; and as these diseases are never cured spontaneously, but require medicines, which act without apparent operation, some have suspected, that the contagious material produces similar matter rather by a chemical change of the fluids, than by an animal process; and that the specific medicines destroy their virus by chemically combining with it. This opinion is successfully combated by Mr. Hunter, in his Treatise on Venereal Disease, Part I. c. i.
But this opinion wants the support of a.n.a.logy, as there is no known process in animal bodies, which is purely chemical, not even digestion; nor can any of these matters be produced by chemical processes. Add to this, that it is probable, that the insects, observed in the pustules of the itch, and in the stools of dysenteric patients, are the consequences, and not the causes of these diseases. And that the specific medicines, which cure the itch and lues venerea, as brimstone and mercury, act only by increasing the absorption of the matter in the ulcuscles of those diseases, and thence disposing them to heal; which would otherwise continue to spread.
Why the venereal disease, and itch, and tenia, or scald head, are repeatedly contagious, while those contagions attended with fever can be received but once, seems to depend on their being rather local diseases than universal ones, and are hence not attended with fever, except the purulent fever in their last stages, when the patient is destroyed by them.
On this account the whole of the system does not become habituated to these morbid actions, so as to cease to be affected with sensation by a repet.i.tion of the contagion. Thus the contagious matter of the venereal disease, and of the tenia, affects the lymphatic glands, as the inquinal glands, and those about the roots of the hair and neck, where it is arrested, but does not seem to affect the blood-vessels, since no fever ensues.
Hence it would appear, that these kinds of contagion are propagated not by means of the circulation, but by sympathy of distant parts with each other; since if a distant part, as the palate, should be excited by sensitive a.s.sociation into the same kind of motions, as the parts originally affected by the contact of infectious matter; that distant part will produce the same kind of infectious matter; for every secretion from the blood is formed from it by the peculiar motions of the fine extremities of the gland, which secretes it; the various secreted fluids, as the bile, saliva, gastric juice, not previously existing, as such, in the blood-vessels.
And this peculiar sympathy between the genitals and the throat, owing to sensitive a.s.sociation, appears not only in the production of venereal ulcers in the throat, but in variety of other instances, as in the mumps, in the hydrophobia, some coughs, strangulation, the production of the beard, change of voice at p.u.b.erty. Which are further described in Cla.s.s IV.
1. 2. 7.
To evince that the production of such large quant.i.ties of contagious matter, as are seen in some variolous patients, so as to cover the whole skin almost with pustules, does not arise from any chemical fermentation in the blood, but that it is owing to morbid motions of the fine extremities of the capillaries, or glands, whether these be ruptured or not, appears from the quant.i.ty of this matter always corresponding with the quant.i.ty of the fever; that is, with the violent exertions of those glands and capillaries, which are the terminations of the arterial system.
The truth of this theory is evinced further by a circ.u.mstance observed by Mr. J. Hunter, in his Treatise on Venereal Disease; that in a patient, who was inoculated for the small-pox, and who appeared afterwards to have been previously infested with the measles, the progress of the small-pox was delayed till the measles had run their course, and that then the small-pox went through its usual periods.
Two similar cases fell under my care, which I shall here relate, as it confirms that of Mr. Hunter, and contributes to ill.u.s.trate this part of the theory of contagious diseases. I have transcribed the particulars from a letter of Mr. Lightwood of Yoxal, the surgeon who daily attended them, and at my request, after I had seen them, kept a kind of journal of their cases.
Miss H. and Miss L. two sisters, the one about four and the other about three years old, were inoculated Feb. 7, 1791. On the 10th there was a redness on both arms discernible by a gla.s.s. On the 11th their arms were so much inflamed as to leave no doubt of the infection having taken place. On the 12th less appearance of inflammation on their arms. In the evening Miss L. had an eruption, which resembled the measles. On the 12th the eruption on Miss L. was very full on the face and breast, like the measles, with considerable fever. It was now known, that the measles were in a farm house in the neighbourhood. Miss H."s arm less inflamed than yesterday. On the 14th Miss L."s fever great, and the eruption universal. The arm appears to be healed. Miss H."s arm somewhat redder. They were now put into separate rooms. On the 15th Miss L."s arms as yesterday. Eruption continues. Miss H."s arms have varied but little. 16th, the eruptions on Miss L. are dying away, her fever gone. Begins to have a little redness in one arm at the place of inoculation. Miss H."s arms get redder, but she has no appearance of complaint. 20th, Miss L."s arms have advanced slowly till this day, and now a few pustules appear. Miss H."s arm has made little progress from the 16th to this day, and now she has some fever. 21st, Miss L. as yesterday.
Miss H. has much inflammation, and an increase of the red circle on one arm to the size of half a crown, and had much fever at night, with fetid breath. 22d, Miss L."s pustules continue advancing. Miss H."s inflammation of her arm and red circle increases. A few red spots appear in different parts with some degree of fever this morning, 23d. Miss L. has a larger crop of pustules. Miss H. has small pustules and great inflammation of her arms, with but one pustule likely to suppurate. After this day they gradually got well, and the pustules disappeared.
In one of these cases the measles went through their common course with milder symptoms than usual, and in the other the measly contagion seemed just sufficient to stop the progress of variolous contagion, but without itself throwing the const.i.tution into any disorder. At the same time both the measles and small-pox seem to have been rendered milder. Does not this give an idea, that if they were both inoculated at the same time, that neither of them might affect the patient?
From these cases I contend, that the contagious matter of these diseases does not affect the const.i.tution by a fermentation, or chemical change of the blood, because then they must have proceeded together, and have produced a third something, not exactly similar to either of them: but that they produce new motions of the cutaneous terminations of the blood-vessels, which for a time proceed daily with increasing activity, like some paroxysms of fever, till they at length secrete or form a similar poison by these unnatural actions.
Now as in the measles one kind of unnatural motion takes place, and in the small-pox another kind, it is easy to conceive, that these different kinds of morbid motions cannot exist together; and therefore, that that which has first begun will continue till the system becomes habituated to the stimulus which occasions it, and has ceased to be thrown into action by it; and then the other kind of stimulus will in its turn produce fever, and new kinds of motions peculiar to itself.
10. On further considering the action of contagious matter, since the former part of this work was sent to the press; where I have a.s.serted, in Sect. XXII. 3. 3. that it is probable, that the variolous matter is diffused through the blood; I prevailed on my friend Mr. Power, surgeon at Bosworth in Leicestershire to try, whether the small-pox could be inoculated by using the blood of a variolous patient instead of the matter from the pustules; as I thought such an experiment might throw some light at least on this interesting subject. The following is an extract from his letter:--
"March 11, 1793. I inoculated two children, who had not had the small-pox, with blood; which was taken from a patient on the second day after the eruption commenced, and before it was completed. And at the same time I inoculated myself with blood from the same person, in order to compare the appearances, which might arise in a person liable to receive the infection, and in one not liable to receive it. On the same day I inoculated four other children liable to receive the infection with blood taken from another person on the fourth day after the commencement of the eruption.
The patients from whom the blood was taken had the disease mildly, but had the most pustules of any I could select from twenty inoculated patients; and as much of the blood was insinuated under the cuticle as I could introduce by elevating the skin without drawing blood; and three or four such punctures were made in each of their arms, and the blood was used in its fluid state.
"As the appearances in all these patients, as well as in myself, were similar, I shall only mention them in general terms. March 13. A slight subcuticular discoloration, with rather a livid appearance, without soreness or pain, was visible in them all, as well as in my own hand. 15.
The discoloration somewhat less, without pain or soreness. Some patients inoculated on the same day with variolous matter have considerable inflammation. 17. The discoloration is quite gone in them all, and from my own hand, a dry mark only remaining. And they were all inoculated on the 18th, with variolous matter, which produced the disease in them all."
Mr. Power afterwards observes, that, as the patients from whom the blood was taken had the disease mildly, it may be supposed, that though the contagious matter might be mixed with the blood, it might still be in too dilute a state to convey the infection; but adds at the same time, that he has diluted recent matter with at least five times its quant.i.ty of water, and which has still given the infection; though he has sometimes diluted it so far as to fail.
The following experiments were inst.i.tuted at my request by my friend Mr.
Hadley, surgeon in Derby, to ascertain whether the blood of a person in the small-pox be capable of communicating the disease. "Experiment 1st. October 18th, 1793. I took some blood from a vein in the arm of a person who had the small-pox, on the second day of the eruption, and introduced a small quant.i.ty of it immediately with the point of a lancet between the scars and true skin of the right arm of a boy nine years old in two or three different places; the other arm was inoculated with variolous matter at the same time.
"19th. The punctured parts of the right arm were surrounded with some degree of subcuticular inflammation. 20th. The inflammation more considerable, with a slight degree of itching, but no pain upon pressure.
21st. Upon examining the arm this day with a lens I found the inflammation less extensive, and the redness changing to a deep yellow or orange-colour, 22d. Inflammation nearly gone. 23d. Nothing remained, except a slight discoloration and a little scurfy appearance on the punctures. At the same time the inflammation of the arm inoculated with variolous matter was increasing fast, and he had the disease mildly at the usual time.
"Experiment 2d. I inoculated another child at the same time and in the same manner, with blood taken on the first day of the eruption; but as the appearance and effects were similar to those in the preceding experiment, I shall not relate them minutely.
"Experiment 3d. October 20th. Blood was taken from a person who had the small-pox, on the third day of the eruption, and on the sixth from the commencement of the eruptive fever. I introduced some of it in its fluid state into both arms of a boy seven years old.
21st. There appeared to be some inflammation under the cuticle, where the punctures were made. 22d. Inflammation more considerable. 23d. On this day the inflammation was somewhat greater, and the cuticle rather elevated.
"24th. Inflammation much less, and only a brown or orange-colour remained.
25th. Scarcely any discoloration left. On this day he was inoculated with variolous matter, the progress of the infection went on in the usual way, and he had the small-pox very favourably.
"At this time I was requested to inoculate a young person, who was thought to have had the small-pox, but his parents were not quite certain; in one arm I introduced variolous matter, and in the other blood, taken as in experiment 3d. On the second day after the operation, the punctured parts were inflamed, though I think the arm in which I had inserted variolous matter was rather more so than the other. On the third the inflammation was increased, and looked much the same as in the preceding experiment. 4th.
The inflammation was much diminished, and on the 5th almost gone. He was exposed at the same time to the natural infection, but has continued perfectly well.
"I have frequently observed (and believe most pract.i.tioners have done the same), that if variolous matter be inserted in the arm of a person who has previously had the small-pox, that the inflammation on the second or third days is much greater, than if they had not had the disease, but on the fourth or fifth it disappears.
"On the 23d I introduced blood into the arms of three more children, taken on the third and fourth days of the eruption. The appearances were much the same as mentioned in experiments first and third. They were afterwards inoculated with variolous matter, and had the disease in the regular way.
"The above experiments were made with blood taken from a small vein in the hand or foot of three or four different patients, whom I had at that time under inoculation. They were selected from 160, as having the greatest number of pustules. The part was washed with warm water before the blood was taken, to prevent the possibility of any matter being mixed with it from the surface."
Shall we conclude from hence, that the variolous matter never enters the blood-vessels? but that the morbid motions of the vessels of the skin around the insertion of it continue to increase in a larger and larger circle for six or seven days; that then their quant.i.ty of morbid action becomes great enough to produce a fever-fit, and to affect the stomach by a.s.sociation of motions? and finally, that a second a.s.sociation of motions is produced between the stomach and the other parts of the skin, inducing them into morbid actions similar to those of the circle round the insertion of the variolous matter? Many more experiments and observations are required before this important question can be satisfactorily answered.